be [cardinal number] years old
The Spanish phrase 'tener [número cardinal] años' translates to 'be [cardinal number] years old' in English. This phrase is commonly used to express someone's age. For instance, 'tener veinte años' means 'be twenty years old'. In Spanish, the verb 'tener' is used to express age, unlike in English where the verb 'be' is utilized.
My sister is ten years old.
This phrase indicates the age of the speaker's sister, highlighting that she is presently ten years old.
We are fifteen years old.
In this instance, the speakers are stating their collective age, which is fifteen years.
The dog is three years old.
This sentence conveys the age of the dog, specifying that it has lived for three years.