An idiom is an expression that cannot be translated literally from one language to another. A number of idioms in Spanish involve the verb tener, and must be memorized.
 

tener...años	to be ...years old
tener hambre	to be hungry
tener sed	to be thirsty
tener frío	to be cold
tener calor	to be hot
tener prisa	to be in a hurry
tener sueño	to be sleepy
tener razón	to be right
no tener razón	to be wrong
tener miedo (de)	to be afraid of
tener ganas (de)	to feel like (doing something)
tener que + infinitive	to have to (do something)