Learn Portuguese (Portugal): De manhã bebo café.

In Portuguese, to say "in the morning", "in the afternoon", or "in the evening", you use the preposition de (of/from). So, de manhã literally means "of morning". You will also use this when giving a specific time, like às oito da manhã (at eight in the morning).

Where is the word for "I" in this sentence?

The word for "I" is eu, but it is left out here. In Portuguese, the verb ending usually tells you who is doing the action. Bebo ends in -o, which is the "I" form of the verb beber (to drink). You can say eu bebo, but it is much more natural to just drop the pronoun.

Why is there no article before café? Should it be o café?

When you are talking about an unspecified amount of something you eat or drink, you leave the article out, just like in English. Bebo café means "I drink coffee" in general. If you said Bebo o café, it would mean "I drink the coffee" (meaning a specific cup of coffee).

Could I say da manhã instead of de manhã here?

Not in this sentence. You use de manhã when just saying "in the morning" as a general time of day. You use da manhã (which combines de and the "the" word a) when linking the morning to a specific hour, which you are learning in this lesson, like às nove da manhã (at nine in the morning).