The floor drain is located in your basement floor and is there to drain any water on your basement floor. It should be located in the lowest part of your basement and is covered with a round, perforated plate.
The cement floors in your basement should be slightly sloped to the floor drain. The floor drain should be connected to the sanitary sewer system and should have a trap.
The trap for your floor drain trap will look very similar to the trap located under your kitchen sink (see example picture below). The pipe underneath the floor drain is shaped in such a way to 'trap' water in the pipe to prevent odours from coming into the home.
If you were to have a flood in your basement from the sanitary sewer system, it would most likely come up the floor drain first because it is the lowest point in the basement.
Check your floor drain twice a year (spring and fall), or if you smell odours (sewer gas) to ensure there is water in the trap. You can do this by looking into your floor drain. If you see water, that is good. If you're not sure, you could always pour some water down the floor drain to ensure there is water in the trap. By ensuring there is water in the trap, you will not get any sewer gas odours coming into your home.