Learn Swedish: Trädet tappar sina grenar på grannens egendom. - The tree drops its branches on the neighbor's property.

In Swedish, when "its", "his", "her", or "their" refers back to the subject of the same clause, you must use the reflexive possessive sin, sitt, or sina. Here, the branches belong to the subject, Trädet (The tree), so we use sina rather than the non-reflexive word dess.

The tree is an ett-word (Trädet). Shouldn't we use sitt?

The choice between sin, sitt, and sina depends entirely on the thing being owned, not the owner. Even though the owner (Trädet) is an ett-word, the things being owned (grenar) are plural. Therefore, we must use the plural form sina.

The word tappar translates to "drops" here, but doesn't it also mean "loses"?

Yes, att tappa means both "to drop" (like dropping a glass) and "to lose" in a physical or natural way (like a tree losing leaves or a person losing teeth). You wouldn't use it for losing a match or an abstract concept; for that, you would use the verb att förlora.

How does the possessive work in grannens egendom?