Learn Spanish (Spain): Para el lunes, ya habremos planificado la primera fase. - By Monday, we will have already planned the first phase.

It is formed using the future tense of the helper verb haber (here, habremos for "we") plus the past participle of the main verb (here, planificado). It translates to "we will have planned" and is used to talk about an action that will be completed before a certain point in the future.

Why is para used here instead of por to say "By Monday"?

When talking about deadlines or a specific point in time in the future, you always use para. It sets the limit for when the action will be finished, just like "by" in English. Using por here would sound like you are doing something during or throughout Monday.

Could I put ya between the two parts of the verb, like habremos ya planificado?

No, in Spanish you can never separate the helper verb (haber) and the past participle (planificado). Adverbs like ya (already) must go before or after the entire compound verb, which is why it is placed right before habremos.

Why do we need the article el before lunes?

In Spanish, days of the week require the definite article (el or los) when you are talking about things happening on or by that day. Unlike in English, you cannot just say para lunes.