Okay I understand that u have been training for a long time or just started training so there is a little advice for u. Exercise that u should be performing in gym.
- Squats
One of the best exercise that targets almost every muscle of ur body. Especially ur core, quads hamstring and glutes. - Deadlifts
As the name given it looks easy before mastering and believe me once u master it voila it will be a piece of cake. Legs and back are the muscles that are targeted.
3.Dumbell bench press
Many will not agree but after doing u will find that dumbell bench presses are very effective than normal rod bench presses
Bonus
Pushups and pullups
These are the exercises that I find most important if u r into fitness because these are capable of creating ur upper body
If u want any other type of info do comment and also comment if u r going to the gym or any kind of fitness related activity and r u doing anyone of these.