I need to know when I use stun on someone but the opponent doesn't break it, why my second stun doesn't work? Do I have to use it after a delay of 10 seconds, more? If the opponent breaks it then I can use my stun and now it works? I think I misunderstand the mechanics lol. I need a lil help there

Is the enemy player's resolve bar full after they break your first stun?

Yes mostly of the time

Once resolve is full you can't stun them (or root them) until the white is completely drained from the bar. Your roots will become slows and your stuns will do nothing other than whatever damage they also apply.

 

Basic strategy is to only completely fill someone's resolve when you know they can't or won't break the stun and give you a full 4 seconds of whatever you want to do. For example, you could white bar someone when you know they've used their breaker already or when you don't think they will break for tactical reasons. Strategically you have more complex options: early in a fight, you might whitebar a healer after a burst phase, thinking they might not use breaker and let you do a little sustained damage. But you also know your next burst window will line up perfectly with them finally having no resolve after 20 seconds or whatever it is. It's far easier to just avoid whitebar until they have used their breaker, though.

If the resolve bar is full, your stuns won’t work.

Also here's a great thread about resolve:

 

https://www.swtor.com/community/showthread.php?t=837220