Se deres sabão às crianças, elas lavarão as mãos sem reclamar.

If you give soap to the children, they will wash their hands without complaining.

Breakdown of Se deres sabão às crianças, elas lavarão as mãos sem reclamar.

• sem: without
• se: if
• a criança: the child
• a: to
• lavar: to wash
• reclamar: to complain
• dar: to give
• a mão: the hand
• o sabão: the soap
• elas: they

Questions & Answers about Se deres sabão às crianças, elas lavarão as mãos sem reclamar.

What is the verb form deres here, and why is it used instead of dás?

deres is the future subjunctive, 2nd person singular of dar (“to give”). In Portuguese, conditional clauses introduced by se referring to possible future situations take the future subjunctive, not the present indicative. So Se deres sabão… literally means “If you give soap…” as a future condition. Using dás would make it present indicative (“If you give soap [now or regularly]…”), which changes the nuance.

Why is there an accent in às before crianças, and what does it represent?

às is the contraction of the preposition a (“to”) with the feminine plural definite article as (“the”). Portuguese merges and accents them:
  a + as → às
So às crianças means to the children.

Why is the main verb lavarão in the future indicative, instead of the present tense?

lavarão is the 3rd person plural future indicative of lavar (“to wash”). It’s used here because the consequence (“they will wash their hands without complaining”) is also projected into the future, tied to the condition. You could paraphrase with a periphrastic future:
  elas vão lavar as mãos…
but simple future lavarão is more concise and formal.

Can we omit the pronoun elas, and why is it included?

Yes, subject pronouns are optional in Portuguese because the verb ending already marks person and number. Here elas is included for clarity or emphasis (“they will wash…”). You could say simply lavarão as mãos sem reclamar, and the meaning stays clear.

Why is the object as mãos used without a reflexive pronoun (e.g. se)?

Portuguese commonly says lavar as mãos for “wash one’s hands” without a reflexive pronoun because the definite article (as) already indicates that it’s the children’s own hands. A reflexive form (lavarem-se as mãos) would be grammatically possible but is archaic or literary.

Why is the verb after sem in the infinitive (sem reclamar)?

When sem (“without”) introduces a verb idea, Portuguese uses the simple infinitive, not a gerund. So you always say sem + infinitive:
  sem reclamar (“without complaining”),
  sem dizer nada (“without saying anything”).
This is a fixed structure.

Could the two clauses be inverted, placing the consequence before the condition?

Yes. Grammatically you can invert:
  Elas lavarão as mãos sem reclamar se deres sabão às crianças.
However, placing the se‐clause first is more natural and highlights the condition.