while sleeping white liquitd comes out?

Hi,
Welcome to the ehealthforum and I am really glad to help you out. What you are having are called wet dreams or nocturnal emissions. They are common during adolescence and early young adult years. they begin only after puberty due to increased hormone production and are completely normal in healthy males.

It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care.

how can to solve it?

You are probably going through puberty right now but don't know. This is natural and happens to all guys. Releasing it yourself while you are awake should reduce this from happening. Your body is going to keep producing it but this isn't as big of an issue of you release before going to bed.