Hi have forgetting problem and I cannot understood any thing and forget quickly and cannot remember it. My age is 29, my name is sandeep, I am a male

Speaking just from my own experience, I know that if I am learning, or being taught something new, that I am totally unfamiliar with, things just don't sink in.

Some things are easier to absorb and process, than other things. It's the 'other things' that aren't processed and understood, that aren't committed to memory.

Things take practise, and learning takes practise. There are ways to improve this process.

Take notes if you are feeling anxious, or unsure of something you are being told, or taught. Don't be shy to ask questions if you are getting some of it, but not parts of it. Ask for more instruction.

Don't panic. Allow your brain to accept the information, even if you don't understand it. It will make sense if you don't force it so much.

One thing is for sure, worrying and being stressed about remembering information, won't help in actually remembering what you want to.

Try to figure out what external forces may be affecting learning. Are you stressed, on medication, not sleeping enough, substance problems, etc.

First would be to check for a medical reason. Are you eating well and getting all of your nutrients and vitamins?
What I would suggest if that is all okay is the following. Be mindful of when you are in a situation. Focus your attention on what is going on in the moment. When your mind wanders bring it back to the situation. No judgments about your mind wandering off just something to the effect "Oh I need to bring my attention back to this". What this does is allow your brain to be focused all of the way on what is happening.
Why I suggest this is because how many times have you driven the same route and found you got there and don't remember the trip? Your brain was not being mindful and probably off in a 1000 different directions. Now if you drive the same route and focus on the here and now bringing yourself back when your mind wanders off you may remember more of the trip.