As others have said, she may well just be a very talkative cat.
One possibility - She may also be calling for the other one. I have two and, if Ripley wants her brother and can't find him, she will cry and wander around for ages. Sometimes he is dozing and can't be bothered answering, so if I want the noise to stop I either play with her myself or wake the dozing one up
The second possibility is that she wants out, because she has been there and it was fun. If you are going to let them out, it is best to stick to a routine. For example, build a cat enclosure and let them go there anytime they want. Or let them out only in daylight hours.
My routine is - they first have to have their collars on. They wait by the shelf the collars are kept. They can go out only when it is light and both of us are already up, generally by 8am or so. They generally come in and out several times during the day. It is late summer here in Australia, and I am outside most of the day, in the garden, or working on the deck. They come visit me, have a stroke, nibble some biscuits. They generally sleep all afternoon, Jonesy close by to me. Ripley, his sister, prefers to nap outdoors under the hedge. If I haven't seen them for a couple of hours, I call and they come to me. From around 5pm I stop work and play with them in the garden, so they run around lots. Often they play tag me/chase me and all I need do is laugh..... Then as dusk gathers, currently around 7,30pm, I call them in. The cat flap is locked, collars come off and they are fed. They do not cry to be let out again - they know the routine. If, for some reason, I take them indoors when they should be allowed out, they kick up a huge racket. Recently, my husband was constructing a concrete slab and they were getting dangerously close to his work, so I locked them in with me. The noise was incredible.....
There are risks in letting them outside, and everyone makes different choices about whether to handle that risk. Whatever you decide to do, if you stay systematic and build a routine they recognise, perhaps you will find, as I have, that they settle into that.
Or, of course, you might just have an especially vocal one and she'll talk away all the time, regardless!