A typical movie is said to have three acts, but this is not a steadfast rule. Film acts are not defined as strictly as play or TV show acts, which are set off with act breaks.
The [johnaugust.com glossary](http://johnaugust.com/glossary) explains that “Since screenplays never show act breaks, an ‘act’ is really a theoretical concept. Screenwriters talk about three acts, meaning ‘the beginning,’ ‘the middle,’ and ‘the end.’”
Per [Syd Field](https://screenwriting.io/who-is-syd-field/), it is not uncommon for people to break the middle act in half: act 2A and 2B.