Learn Portuguese (Portugal): Os pertences, o turista continuou a descrevê-los. - The belongings, the tourist continued to describe them.

This is called left-dislocation or topicalization. To emphasize what is being talked about (the topic), Portuguese speakers often move the object to the very beginning of the sentence. In English, we might say "As for the belongings..." or just use our tone of voice, but in Portuguese, physically moving the object to the front is a standard way to show this focus.

If we already established we are talking about Os pertences, why do we need -los at the end? Isn't that redundant?

It feels redundant in English, but it is required in Portuguese. When you move a direct object to the front of the sentence to emphasize it, you must leave a "resumptive clitic" (a pronoun) in the object's normal position. Here, -los acts as a mandatory grammatical placeholder that points back to Os pertences.

Why does the pronoun become -los instead of -os, and why does descrevê have a circumflex accent?

When a direct object pronoun like -os attaches to an infinitive verb ending in -r, the verb drops the -r and the pronoun gains an L (becoming -los). Because the verb descrever loses its final letter, we must add a circumflex accent to the final e to preserve its original stressed sound, resulting in descrevê-los.

Why is there an a between continuou and descrevê-los?