For example, we say that life has its ups and downs – the ups are the good parts and the downs are the bad parts.
When someone feels high, it means they are feeling good. To improve your position at work is to 'move up'. A better position is a higher position.
To dress in nice clothes is to dress up. Someone who is wealthy and cultured is seen as 'high class'. An expensive product is a high-end product.
Of course, 'up' is not always used in a symbolic way. For example, when we say 'look something up in the dictionary', up has no symbolic meaning.