Sombra is a very sneaky character with a lot of opportunities if played right. She can prevent enemy retreats and engages with her Hack and EMP. She can do 48-160 damage per second if all 20 shots per second are hit. She can do up to 144-480 damage per magazine. But the damage isn't everything when it comes to Sombra, her kit is mainly utility.

• Machine Pistol

Machine Pistol isn't meant for heavy damage output, it should only be used if there are low health targets or to provoke healers and supports.

• Hack

Hack is a very useful ability if used properly and pretty straight forward. It can be useful against an enemy Reinhardt

• Stealth

There isn't much to say about Thermoptic Camp other than it is a good way to sneak past enemy forces to take out a Teleporter or a Shield Generator

• Translocator

Translocator is also mainly used to get to safe areas or engage with EMP. (Note that teleporting with Translocator doesn't break Thermoptic Camo)

• EMP

EMP is an AoE ability that hacks everything within 15 meters of Sombra if there isn't a wall or a large object between them. EMP can be very effective if used together with a Zarya or Reinhardt, because of their ultimates.

Sombra is a very seasonal character, devastating sometimes and other she is a terrible pick.
I personally wouldn't pick Sombra on control point maps.
She can is viable on some of the capture point maps.
Where I find her strong is on most of the payload maps because she can make it hard for enemies to retreat if she has hacked the right health packs.
Let's use Hollywood as an example if the enemy has a Reinhardt which they have in, and there isn't anyone on the high ground,
then it is very easy for Sombra to throw a Translocator and teleport while she has Thermoptic Camo activated. While the rest of the team prepares to engage,
Sombra should start hacking Reinhardt to make it easier to get a good Earthshatter or Graviton Surge.