The tricky thing is that 厉害 can also be sarcastic. But basically it is more commonly used in a good way if you give or receive such comment in person. There is really no sure way to know which is which unless a context is provided. Try compare the differences with those between "frightful" and "frightfully", "terrible" and "terribly".

i want to say,厉害mean. [emoji]you know?it is a good and positive Word. for example,if you meet someone are good at something,you can say“你非常厉害”

厲害 Usually means awesome. 很厲害 usually means awesome and it is positive If you speak Chinese to a Chinese person, they might say 你中文說得好好啊，厲害！You speak great Chinese, awesome! It can also be used to describe like weather. 昨天下雨了，下得很厲害 It rained really hard yesterday Laurence

你抬起了这么重的东西，好厉害。 你会打女人了？可真厉害。

厉害used in negative way: 病的厉害（seriously ill），咳得厉害（coughing heavily），疼得厉害（unbearable pain） However，you cannot judge whether 你是很厉害的人means positive or negative, because 厉害here can mean high capabilities or sly/vicious.It all depends on the context. hope I helped:) all the best for your mandarin learning