Learn Hardcore Portuguese (Portugal): As tuas botas são mais leves do que as minhas.

In European Portuguese it’s very common to include the definite article before a possessive adjective. So as tuas botas (lit. “the your boots”) is standard. Omitting the article (tuas botas) sounds less natural or more informal.

What’s the difference between tuas and suas for “your”?

Tuas is the 2nd-person singular informal possessive (you = tu). Suas is 3rd-person singular or the formal 2nd person (you = você) and also “his/her/their.” If you’re speaking to a friend, you use tuas botas. If you were speaking formally (você) or referring to someone else’s boots, you’d use suas botas.

Why is the verb são (from ser) used here instead of estão (from estar)?

Ser expresses an inherent or permanent characteristic—in this case, weight (a lasting property of the boots). Estar would imply a temporary state (e.g., if the boots were wet or dirty). Since weight isn’t a transient condition, you use são.

Why is it mais leves and not mais leve?

Botas is feminine plural, so the adjective leve must agree in number (and gender). The plural of leve is leves, hence mais leves (“lighter [plural]”).

Why do we say mais leves do que instead of just mais leves que?

The full comparative construction in European Portuguese is mais…do que. Informally, you might hear mais leves que, but the prescriptive norm is mais leves do que (“lighter than”).

At the end we read as minhas—why is the noun botas omitted?

This is an example of ellipsis: once you’ve mentioned botas, you can replace it with the possessive phrase as minhas to avoid repetition. It literally means “the ones that are mine.”

Could the word order change? For example Tu as botas leves mais do que as minhas?

No. Portuguese requires the article + possessive + noun order (As tuas botas). The comparative são mais leves do que must follow the verb. Changing the order would be ungrammatical.