The circuit essentially just makes a copy - at the output - of the the
input voltage, Vin. It does that without drawing
any current from wherever the input voltage terminal is attached.
However, at the output terminal you can draw whatever amount of current
the operational amplifier can supply (and that depends upon the kind of
operational amplifier you use).
There are many situations where you do not want to draw current from a circuit (i.e. "load" the circuit). Some of those situations are:
If the difference between V+ and V- is negligibly small so that V+ = V- we must have:
Here is a drawing of what the circuit should look like on a circuit board.
In this drawing we have shown connections that are actually made under
the board - connections that are not visible from the top of the board.
Those are shown with lighter lines that go through the connecting "holes"
in the drawing. They are there to show you how the various wires
are actually connected to the operational amplifier through metallic connections
under the board. And, don't forget, the integrated circuit is a 741
operational amplifier chip.