Learn Spanish (Latin America): La jirafa es alta; en el safari, la vi comiendo. - The giraffe is tall; on the safari, I saw her eating.

With verbs of perception like ver (to see), using the gerund (comiendo) emphasizes that the action was ongoing at that exact moment—you saw the giraffe right in the middle of eating. If you used the infinitive (la vi comer), it would mean "I saw her eat," which can imply you witnessed the entire action from start to finish, or it just states the event as a simple fact.

Since there is a gerund (comiendo), could I attach the la to the end of it and say vi comiéndola?

No, you can't do that here. While pronouns can often attach to gerunds, in this sentence la is the direct object of the verb ver (you saw the giraffe). It is not the object of comer (the giraffe isn't being eaten!). Because la belongs to vi, it must go right before it: la vi comiendo.

The English translation says "I saw her". Does la mean we know the giraffe is female?

Not necessarily! In Spanish, the noun jirafa is always feminine, regardless of the animal's actual biological sex. Because the noun is feminine, you must use the feminine direct object pronoun la to say "saw it" or "saw her", even if it happened to be a male giraffe.

Why do we use es (from ser) instead of (from ) for "is tall"?