"Mi abuelo siempre se levanta a las cinco."
Translation:My grandfather always gets up at five.
That's just the way it is. :-D
To get up = levantarse. It's a reflexive verb (indicated by the se on the end of the infinitive). Levantar means something else if you leave out the reflexive pronouns. (Check a good dictionary. Spanishdict.com is one.)
When telling time, use las before the hours two through twelve, and la before one (una).
A la una = at one (o'clock)
Es la una = It's one (o'clock).
A las doce = at twelve (o'clock)
Son las doce = Its twelve (o'clock).
The articles are not translated.
More on reflexive verbs and telling time: studyspanish.com (Grammar Unit Five).
"Levantar" means to lift or raise something up. This can be used normally with an object, but you can use it with me/te/se when you want to refer to "getting up". "Me levanto" means "I lift myself", or "I get up".
For the second question, imagine that "horas" follows the number of hours. If it's more than one hour, then it's "las". People probably used to always say "hora/horas" when talking about the time. They don't anymore, but the grammar stayed the same.