I figured it out on my own. In case anyone stumbles across this in the future and is in the same spot I was of not knowing how to even interpret a picture like this, here's my explanation.

So 'a' and 'b' are transistors. They can either be 'on' or 'off'. If a transistor is on, that means electricity from the battery (in this example Vcc) is able to pass through them and continue following the line. If a transistor is off, the electricity from the battery doesn't continue down the line. Electricity from the battery flows in a leftwards, counter clockwise direction. The truth table for this particular picture is as follows:

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a     b     F
0     0      0 - 'a' and 'b' are off, so no voltage can pass through either a or b, so no electricity goes to F
0     1      1 - 'a' is off, but 'b' is on. This means electricity will flow into F.
1     0      1 - 'a' is on but 'b' is off. Since 'a' is on, electricity will flow through 'a' and hit the final transistor before F. Therefore, F will have electricity flowing to it.
1     1      1 - 'a' and 'b' are both open, so electricity will flow through these transistors and hit the final transistor before F. Since the final transistor is ON, F will have electricity flowing to it.

F will always return 1 unless both 'a' and 'b' are off.