The Ready action is described on page 72 of the Player's Basic Rules. It allows you to ready a single action or move that you can take as a reaction to a trigger you choose when you take the Ready action.
Then, you choose the action you will take in response to that trigger, or you choose to move up to your speed in response to it. Examples include “If the cultist steps on the trapdoor, I’ll pull the lever that opens it,” and “If the goblin steps next to me, I move away.”
So you can only Ready either a single action or a move up to your speed. This action can be any action, so you can Ready the Attack action. However, you can't use your Extra Attack ability when you take the Attack action as a reaction, because:
Beginning at 5th level, you can attack twice, instead of once, whenever you take the Attack action on your turn.
Since you can only Ready a single action, you can't Ready a bonus action as well as an action, and you can't Ready a bonus action. (Even if you could, you can only take a bonus action on your turn.) The Ready action is an action, though, so you can still move and/or use a bonus action on the turn when you use the Ready action.