So in an OP AMP, one of the main features is the feedback loop that goes from the output to the input. What does that do exactly, like how does that contribute to the amplifying of electric signals?
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The feedback loop isn’t what’s creating the amplification. That’s generally used to create non-linear functions that allow you to do analog derivatives and integrals. This allows us to use them to solve differential equations, which is useful because most analog control problems can be expressed as differential equations. You will probably have a specific control theory course somewhere in your engineering degree.
How amplifiers actually work:
Inside your amplifier, there are electrical devices called transistors. Transistor are basically voltage-controlled resistors. They have three terminals: gate, source and drain. The amount of voltage at the gate terminal determines the resistance between the source and drain. You input signal goes to the gate terminal, the source terminal is connected to a power supply and the drain terminal is connected to the output. Adjusting the voltage at the gate terminal changes the resistance between the source and drain terminals, allowing to adjust the voltage drop from the power supply over the transistor, leaving the voltage you want at the output. In the idealized model used in op amps, the external power supply is dropped and all the awful details of the transistor’s actual operation are ignored.
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