I want to note the person you asked replied with a Wikipedia page. This is interesting cause: pedantically this is not a source of that statistic - the source is the study the Wikipedia page references.

Which - there is no study from the FBI. (Afaict) The intended stat appears to be from a 1990s study which predicts differently than observed. With some particularly damning data from 2015.

Additionally, there are two interesting notes

A "survey about firearms and suicide completed by 150 firearms researchers found that only 8% of firearm researchers agreed that 'In the United States, guns are used in self-defense far more often than they are used in crime'."

"the FBI reported that guns were used in 35 criminal homicides for every defensive ("justifiable") homicide."

Which seems like important context for the usual discussions that stat comes up in.