can u tell me what does it mean plz !!!

hello , i’m confused in the meaning of the word “unless” , i did some exercises on it but i still don’t know its exact meaning & when to use it. !!!
Can u help me plz ?!
thnx in advance !!!

hey buddy

              unless means   ( if  not /  if you dont)

                  for example  :   unless i sleep well, i cant

                 be fresh the next day. 

it means   ===   if not

if it is not  cold , i will  go out

unless it is cold , i will go out 

i hope it is clear

thnx a lot , i think that i got it.

Do you say “Unless you read a lot, you will not be good in English” or do you say “Unless you read a lot, you will be good in English”. The first statement appears to me to be the correct one. The Cambridge Online Dictionary has this to say:

 Unless    (conjunction) = except if

You can't get a job unless you've got experience (= you can only get a job if you have experience).