"It is an enormous bear!"
Translation:¡Es un oso enorme!
Es (ser) is the permanent "to be," and esta (estar) is the temporary "to be." So you use ser for things like "I am (soy) tall" or "I am (soy) American." Estar is temporary. You use it mostly for places and feelings. "I am (estoy) at school" or "I am (estoy) angry." There's a nifty little poem, if it helps "how you feel or where you are, always use the verb estar. Who you are and where your from, use ser--the other one!" For what it's worth, you get a feel for it the more you use the language and it gets to the point where you don't have to think about it.