18 hands at the withers
well dressed and brushed
hooves shining and tail combed
happy and smiling, a gleam in her eye


18 hands means she's a bit over 6 feet to her back

Her head is more like 8 feet or more from the ground


She does go 'into season' from time to time and any horse-based character would be aware of this, the easiest way for others to know would be if she moves her tail and there's anything besides plain brown horsehair visible, she's ready for anything that will fit


she's a horse, yes it'll fit

If she's not in season and searching for a stallion or the closest thing to one, she's like any other human and acts accordingly, be nice to her and she just might be nice to you.