Hey! I'm not exactly sure which part of the song lyrics you are having problems with. What is your first language? If it's spanish then I could help you understand by comparing the words/phrases from English to Spanish.

Anyways...

I see you have (?) after two words, so I am going to assume those are the two phrases/words you're having trouble with.

I want to sing you a wonderful song(?)

I'm not sure which part is giving you trouble. I'm guessing "Wonderful" because that seems, to me, to be the trickiest part of this section. Wonderful means "full of wonder" as the name implies. Wonder means something great, something marvelous. So this part wants to say that he is going to sing you (us, the audience) an awesome/great/cool song

And if you see me, please don't squash me. I want to be on your foot(?) all

Here I'm guessing you either 1) had trouble with "squash" or with "be on your foot". If not, please let me know which gave you problems.

Squash means to destroy, crush or to smash. (do those verbs help?) Since Lucas is a spider, he is saying that he does not want us to kill him by squashing him, or in other words, by not hitting him hard.

If you had trouble with "I want to be on your foot", that is referencing the previous line I just talked about. Since the spider does not want us to kill him, he wants to stay on our foot, or in other words, he wants to rest, stay, or not leave our foot. If foot gave you trouble, that is the part of the body you put shoes on

hope this helps, please ask questions if I didn't clarify what was giving you problems!