Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keywords are activated abilities; they have colons in their reminder text.

Cards with basic land types intrinsically have the appropriate mana ability, even if it isn't printed in the card's text box. Mirran Safehouse also gains those abilities. For example, if there is a Plains in your graveyard, Mirran Safehouse has "{T}: Add {W}," even though that may not be printed on the Plains itself.

If an activated ability of a land card in a graveyard references the card it's printed on by name, treat Mirran Safehouse's version of that ability as though it referenced Mirran Safehouse by name instead.

Mirran Safehouse gains only activated abilities, including activated mana abilites. It doesn't gain keyword abilities (unless those keyword abilities are activated), triggered abilities, or static abilities.