A phrasal verb is a verb with two parts; the verb and a preposition. The preposition changes the meaning of the verb - to turn on a light is different from to turn a corner.
Is there an easy way to learn phrasal verbs? Not if 'easy' means without practice. Phrasal verbs are tricky for English language learners because there are no universal rules. They are the inner secrets of the language; available only to those with the curiosity and patience to discover them.
There are, however, a few useful guidelines that can help - see here:
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Ultimate Phrasal Verb Book
English Phrasal Verbs in Use: Advanced
Oxford Phrasal Verbs Dictionary (Elt)
Learn 100 Most Frequent and Useful Phrasal Verbs in English in Six Easy Steps.