A1 · Who you are, and how you are today
Ser vs estar
Ser is the long story: identity, origin, profession, the time. Estar is the weather of the moment: location, mood, the coffee being hot. Mix them and you sound foreign; keep them apart and Portuguese opens.
Sou alemão. Estou em Lisboa.
I am German. I am in Lisbon (right now).
A loja é grande. A loja está fechada.
The shop is big. The shop is closed (today).
São três horas. Estou cansado.
It's three o'clock. I'm tired.