What is a major way that the executive branch can act as a check on the legislative branch?

The executive branch can check the power of the legislative branch through the power of a veto.

The legislative branch, which consists of the Senate and House of Representatives, have the power to pass laws. However, before these laws become official, the executive branch (aka the President) has the ability to read over the laws. The president then has the power to veto (reject) any bill passed by Congress that he/she does not want to become law.