I think you mean leave (an absence from work, which is a non-countable noun), not leaves (appendages that grow on plants).
"You can take random leave or same day leave. without informing your seniors earlier."
Please check.
You can take a personal leave without getting permission in advance. I had to guess what you meant by random leave. Do you think I guessed right?
Is my sentence totally incorrect?
No, but random leave is not a term I'm familiar with. If you mean a day off without notice then personal leave or, in AmE, a "personal day off" would be suitable. The rest of the sentence was a little oddly worded but comprehensible.
Don't let this upset you. Learning foreign languages is difficult, and writing in one naturally is the hardest part to learn. You're making good progress.