What should I do if the Chinese pinyin n and l are not clear?

When you pronounce N, the whole tip of the tongue covers the upper gum, so that air can come out of the nasal cavity.

When you pronounce L, your tongue is tight (but relaxed). Tap the tip of the tongue, and gum air flows from the mouth. If you want to hear the difference, try to spell some Chinese words, such as milk niu nai (very nasal) and leaving Li Kai.

Because n is emitted through the nasal cavity, don't block your nose when you send l, and try to let the air flow out through your mouth. If you find your pronunciation stale or difficult to pronounce, you still have a nasal sound.