What is a fermata and how does it work?

Explanation:

Adding on the previous answer, yes, fermata is when a note is held longer than the sheet music says.

It may not necessarily be in singing, but also any instrument, whether it can "hold" a sound or not. For example, a guitar string may no longer ring, but the note is technically "held".

Usually, you look at the conductor to gesture how long to hold the note until muting.

It looks like Ω with a dot in the centre.