Learn Swedish: Hon tittar på hotet framför sig. - She looks at the threat in front of her.

In Swedish, when a location phrase like framför refers back to the third-person subject of the sentence, you must use the reflexive pronoun sig. Even though English says in front of her, Swedish requires you to say in front of herself. If you used henne here, it would mean she is looking at a threat in front of a completely different woman.

Would the pronoun change if the subject was jag instead of hon?

Yes. The reflexive pronoun sig is only used for third-person subjects. If the sentence was about you, the pronoun would match the subject: Jag tittar på hotet framför mig.

What is the base form of the word hotet?

The base form is the neuter noun ett hot which means a threat. To make it definite, meaning the threat, you add the suffix -et to the end of the word, giving us hotet.

Can I separate tittar and på and say Hon tittar framför sig på hotet?

It is much more natural to keep the verb phrase tittar på together directly before its object. The object is hotet, so Hon tittar på hotet is your core action. The phrase framför sig just adds extra information about where the threat is, so it naturally sits at the end.