A more thorough explanation:

Textualism is a way of interpreting laws that says we should only look at the words of the law itself, and not try to guess what the lawmakers meant or what they were trying to accomplish. This means that we should only use the plain meaning of the words in the law to figure out what it means.

For example, if a law says "no dogs allowed in the park," a textualist would say that means exactly what it says - no dogs are allowed in the park. They wouldn't try to guess why the lawmakers made that rule or what they were trying to accomplish by it.

Some people think that textualism is a conservative approach to the law, because it doesn't take into account the intentions or goals of the lawmakers. However, sometimes applying textualism can lead to surprising or progressive outcomes.

One example of this is the case of Bostock v. Clayton Cnty., which was decided by the U.S. Supreme Court in 2020. In that case, the court had to decide whether it was legal for employers to discriminate against employees based on their sexual orientation or gender identity. Justice Neil Gorsuch, who is often seen as a follower of the late Justice Antonin Scalia's textualist approach, wrote the opinion for the court. He argued that the plain meaning of the words in the law that prohibits employment discrimination based on sex also applies to discrimination based on sexual orientation or gender identity. This was a surprising and progressive outcome, because many people had assumed that the law only applied to discrimination based on biological sex.