Learn Italian: La sua carriera continua da dieci anni. - His career has been continuing for ten years.

We use da because his career is still ongoing. In Italian, da is used for actions that started in the past and are still happening now. If you used per here, it would mean the career lasted for ten years but is now over (a completed duration).

Why is continua in the present tense when the English translation says "has been continuing"?

In Italian, when you talk about an action that started in the past and is still happening right now, you use the present tense along with da. You can think of it literally as "His career continues since ten years ago."

If the English translation says "His career", why do we use the feminine word sua?

In Italian, possessive words like suo and sua must agree with the gender of the thing being owned, not the owner. Since carriera (career) is a feminine noun, it requires the feminine sua, even though it belongs to a man. Note that it would also be La sua carriera if it were her career!

Why is there a La before sua carriera?