Whether it's a lead instrument on a pop track or the drum kit on a rock track. The truth is that you need to quantize in order to make your tracks sound pro. Unless you're working with amazing session players that can lay down incredible tracks after two takes, your tracks will never sound pro unless you do.

What does it mean to quantize drums?

The process results in notes being set on beats and on exact fractions of beats. The purpose of quantization in music processing is to provide a more beat-accurate timing of sounds. Quantization is frequently applied to a record of MIDI notes created by the use of a musical keyboard or drum machine.

Should I quantize vocals?

You can't quantize an audio file unless the timing is super tight. This is not recommended to do to vocals because of the nature of the sustained notes and pitch fluctuations. They're not like drums. You need to make sure that the tempo is right first and then you can try to do other stuff with it.