Here are a pair of commentaries drawn from here
Adam Clarke's Commentary:
Finally, brethren - The object of the apostle is to recommend holiness and righteousness to them in every point of view; and to show that the Gospel of Christ requires all its professors to have the mind that was in Christ, and to walk as he himself also walked. That they were not to attend to one branch of righteousness or virtue only, but to every thing by which they might bring honor to God, good to their fellow creatures, and credit to themselves.
*Whatsoever things are true *- Ὁσα - αληθη· All that is agreeable to unchangeable and eternal truth. Whether that which is to be learned from the nature and state of created things, or that which comes immediately from God by revelation.
Whatsoever things are honest - Ὁσα σεμνα· Whatever is grave, decent, and venerable. Whatever becomes you as men, as citizens, and as Christians.
Whatsoever things are just - Ὁσα δικαια· Whatsoever is agreeable to justice and righteousness. All that ye owe to God, to your neighbor, and to yourselves.
Whatsoever things are pure - Ὁσα ἁγνα· Whatsoever is chaste. In reference to the state of the mind, and to the acts of the body.
Whatsoever things are lovely - Ὁσα προσφιλη· Whatsoever is amiable on its own account and on account of its usefulness to others, whether in your conduct or conversation.
Whatsoever things are of good report - Ὁσα ευφημα· Whatsoever things the public agree to acknowledge as useful and profitable to men; such as charitable institutions of every kind, in which genuine Christians should ever take the lead.
If there be any virtue - If they be calculated to promote the general good of mankind, and are thus praiseworthy;
Think on these things - Esteem them highly, recommend them heartily, and practice them fervently.
Gill's Exposition of the Whole Bible:
Finally, brethren, whatsoever things are true,.... To close all with respect to the duties of Christianity incumbent on the professors of it, the apostle exhorts to a regard to everything that is true; that is agreeable to the Scriptures of truth, to the Gospel the word of truth, or to the law and light of nature; and whatever was really so, even among the very Heathens, in opposition to falsehood, lying, and hypocrisy
whatsoever things are honest; in the sight of men; or grave, or "venerable" in speech, in action or attire, in opposition to levity, frothiness, or foppery:
whatsoever things are just; between man and man, or with respect both to God and men; giving to God what belongs to him, and to man what is his due; studying to exercise a conscience void of offence to both, in opposition to all impiety, injustice, violence, and oppression:
whatsoever things are pure; or "chaste", in words and deeds, in opposition to all filthiness and foolish talking, to obscene words and actions. The Vulgate Latin and Arabic versions render it, "whatsoever things are holy"; which are agreeable to the holy nature, law, and will of God, and which tend to promote holiness of heart and life:
whatsoever are lovely; which are amiable in themselves, and to be found even among mere moral men, as in the young man whom Christ as man is said to love, Mark 10:21; and which serve to cultivate and increase love, friendship, and amity among men; and which things also are grateful to God and lovely in his sight, in opposition to all contention, strife, wrath, and hatred:
whatsoever things are of good report; are well spoken of, and tend to get and establish a good name, which is better than precious ointment, Ecclesiastes 7:1; for though a good name, credit, and reputation among men, are to be sacrificed for the sake of Christ when called for; yet care is to be taken to preserve them by doing things which may secure them, and cause professors of religion to be well reported of; and which beautiful in all, and absolutely necessary in some:
if there be any virtue; anywhere, among any persons whatever, in opposition to vice:
and if there be any praise; that is praiseworthy among men, and deserves commendation, even though in an unjust steward, Luke 16:8, it should be regarded. The Vulgate Latin adds, "of discipline", without any authority from any copy. The Claromontane manuscript reads, "if any praise of knowledge":
think on these things: meditate upon them, revolve them in your minds, seriously consider them, and reason with yourselves about them, in order to put them into practice.