Eu não entendi esta parte da lição.

I did not understand this part of the lesson.

Breakdown of Eu não entendi esta parte da lição.

• eu: I
• não: not
• esta: this
• entender: to understand

Questions & Answers about Eu não entendi esta parte da lição.

Why is eu included here? Can I leave it out?

Yes, you can often leave eu out in Portuguese because the verb form entendi already shows that the subject is I.

So both of these are natural:

• Eu não entendi esta parte da lição.
• Não entendi esta parte da lição.

Including eu can add clarity, emphasis, or contrast, such as I didn’t understand it, but maybe someone else did.

Why is não placed before entendi?

In Portuguese, não normally goes directly before the verb it negates.

• Eu entendi = I understood
• Eu não entendi = I did not understand

This is the standard word order in simple sentences.

What tense is entendi?

Entendi is the preterite form of entender. In Brazilian Portuguese, the preterite is commonly used for a completed action in the past.

So entendi means:

• I understood
• or, in context, I did understand / I got it

With não, it becomes I didn’t understand.