A more thorough explanation:

A line-item veto is a power given to the executive branch to cancel specific parts of a bill, usually spending provisions, while signing the rest of the bill into law. For example, if a bill includes funding for a new highway and a new park, the executive could use a line-item veto to cancel the funding for the park while still signing the funding for the highway into law.

While some states give their governors a line-item veto, the Supreme Court has declared a federal line-item veto unconstitutional. In the case of Clinton v. City of New York, the Supreme Court ruled that the line-item veto violated the Presentment Clause of the Constitution, which requires that the President either sign a bill into law or veto it in its entirety.

Overall, the line-item veto is a tool that allows the executive to have more control over the budget and spending decisions of the government. However, it is important to balance this power with the constitutional requirements for the legislative process.