In English, if a bodyguard hides a radio behind him, or a president looks in front of her, we use standard object pronouns like "him" and "her". Swedish is more specific. Whenever a spatial location is relative to the subject of the sentence, Swedish requires a reflexive pronoun.
The Third Person: Sig
For third-person subjects (he, she, it, they), the reflexive pronoun is always sig. You will see this frequently with spatial prepositions like bakom (behind), framför (in front of), and bredvid (next to).
Fixed Spatial Expressions
Swedish also uses sig in a few fixed spatial expressions where English doesn't use a pronoun at all. The most common are se sig omkring (to look around) and ta med sig (to take with, or bring).
The Second Person: Dig
For first- and second-person subjects (I, you, we), Swedish just uses the standard object pronouns (mig, dig, oss, er) as reflexives. If the subject is du (you), the spatial phrase uses dig.
Staying Vigilant
You might need several spatial reflexives in the same sentence. As long as they all refer back to the third-person subject, keep using sig.