And clause are use to combined two or more than two condition together. In this case you need must be true both condition then return the result otherwise no return any result.
Suppose you want to get only those employee record who have more than 30000 salary and more than 5 year experience in that case you can combined these two condition by using and clause.
SELECT columns FROM tables WHERE condition 1 AND condition 2;
SELECT * from Employee WHERE salary>30000 AND experience>5;
Result after using AND clause: Here ony show those employee detail who have more than 30000 salary and more than 5 years experience