Learn Italian: Il suo posto è qui.

In Italian, possessive adjectives like suo almost always need a definite article (like il or la) in front of them. You literally have to say 'the his place'.

The translation says 'His place', but could Il suo posto also mean 'Her place'?

Yes! In Italian, the possessive adjective agrees with the thing being owned, not the owner. Since posto (place) is a masculine word, you use the masculine form suo, regardless of whether the place belongs to a man or a woman.

If Il suo posto can mean his place or her place, how do we know who it belongs to?

Usually, the context of the conversation makes it clear who you are talking about. If it is completely ambiguous and you need to be specific, an Italian might say Il posto di lui (the place of him) or Il posto di lei (the place of her), but Il suo posto is the standard, most common way to say it.

Why does è have an accent mark here?

The accent mark is crucial because it changes the meaning. With the accent, è means 'is' (from the verb essere, to be). Without the accent, e just means 'and'.