Glossary
Setup
In one line: How a player or team is arranged on a site, with positions and utility ready.
What it means
A setup is the prepared arrangement of a defense (or a post-plant): who stands where, which angles they watch, where the traps are, what utility is ready and for what. Sentinels often talk about their "setup" meaning where they place their abilities.
A good setup covers the entrances, lets defenders support each other (crossfire, trade) and is not always the same: a setup repeated every round becomes a map for the attackers.
An example
The sentinel puts a trap at the main exit and a camera watching the site. A teammate takes an angle that covers the trap. When the attack comes in, the trap slows them and the teammate picks them off.