Some prepositions are used to show direction in english language. What is the difference between them ?

what is the difference between walk along and walk on in english language? Does along mean parallel to something ing english language?

what is the difference between turn to left and turn on in enlish language ? Can anyone explain the difference between them ?

I myself am Umashankar sinha. I am trying to learn english language. Now i have completed my study. I want to familiar with this language as i am with my hindi