Learn Spanish (Latin America): Al ver al enemigo, lo esquivas.

In Spanish, combining al with an infinitive verb like ver creates a time clause meaning 'upon seeing' or 'when seeing'. Because the infinitive verb isn't conjugated to a specific person, we naturally rely on the second half of the sentence (lo esquivas) to understand that 'you' are the one doing the seeing.

Why is the word 'al' used twice in a row in 'Al ver al enemigo'?

They look identical but do completely different jobs! The first al creates the 'upon seeing' time clause. The second al is a contraction of the personal a (which is required because the enemy is a person) and the definite article el (the) right before enemigo.

Why do we use the pronoun 'lo' instead of 'le' for 'him'?

The verb esquivar (to dodge) takes a direct object because you are directly acting upon (dodging) the person, not doing something to or for them. Because of this, we use the direct object pronoun lo (him) rather than the indirect object pronoun le.

Could I just say 'Cuando ves al enemigo' instead?

Yes, absolutely! Cuando ves al enemigo means 'When you see the enemy' and is perfectly correct. Using al ver is just a slightly more concise way to say it, very similar to choosing 'Upon seeing' instead of 'When you see' in English.