pls explain the perfect market competition in thi explain the freedom of entry and exit and also explain the the short run and long run

Both the concepts have been extensively covered in our study material. 

For the topic of Freedom of Entry and Exit under Perfect Competition Market, go through the Chapter-4 (The Theory of Firm under Perfect Competition), Lesson- 2 (Perfect Competition and Its Features) of Microeconomics.

For the topic of Short Run and Long Run Equilibrium, go through the  Chapter-4 (The Theory of Firm under Perfect Competition), Lesson- 4 (Equilibrium and Perfect Competition – Short Run and Long Run) of Microeconomics.

If you find any kind of difficulty, then do let us know.