Sometimes you just need a few words in French and you can make a difference to someone's day. Bonne journée has so much more meaning than it does in English but have a nice day is still a nice thing to say. You won’t get many marks for using an adjective like bon as it is one of the first words you learn. The easiest way to say you don’t like something is to say it is pas bon but a greater vocabulary is always useful.
A nice person is sympathique but you have to remember that the French can’t pronounce th so it sounds like there is no h. If you struggle with pronunciation then you could stick with sympa for the same effect. Nice may mean kind, so aimable may be the word you are looking for. Nice-looking is beau or belle but you could guess this by thinking about the word you are using.
Life is so much better if you are using words that mean nice but occasionally things aren’t so nice. Détester is a verb that means to hate but you could probably guess that. There are so many other words for describing things you like and dislike and the more you learn the better, but don’t forget bon or détester.
A bientôt