...
An operational amplifier, as the name suggests , amplifies signals. More specifically, it is an a voltage amplifier with differential inputs, and usually a single-ended output(there is one output). In the diagram below, Vs+ and Vs- are the supply rails for the amplifier, so usually Vs+ = Supply Voltage and Vs- = Ground.
...
If it wasn’t clear already, op-amps operate on analog inputs, and can be used to amplify/attenuate these inputs and carry out mathematical operation(addition, subtraction, differentiation and integration, yes it can do calculus). Because of this, you’ll see opamps encountered in many circuits and ICs. Ideally, an operational amplifier will only amplify the difference in voltage between the two, which is called differential input voltage. The output Vout is governed by this equation here:
...