"every bill which shall have passed the house of representatives and the senate, shall, before it become a law, be presented to the president of the united states: if he approve he shall sign it, but if not he shall return it, with his objections to that house in which it shall have originated, who shall enter the objections at large on their journal, and proceed to reconsider it."

the quote above reflects the system of checks and balances in that.

if the president vetoes a bill, congress cannot override the veto

neither the president nor either house of congress has complete control over whether a bill becomes a law

the vice president can stop the passing of a bill from the senate to the house

if the president vetoes a bill, he sends it back to the house of representatives, which can override the veto