Often people assume that the meaning of symbols is easier to comprehend than written text. Most of the time, this assumption is wrong.
In the same way that any foreign language must be learned, the idiom of symbols must also be learned. Some symbols or characters are immediately obvious, others require a table with an explanation.
However, we pick up a lot of knowledge about symbols just by looking around in the town where we walk or using public transport. And when everybody knows the meaning of a certain symbol, it communicates a lot quicker than written language. Especially when many languages are used in one place, for example at an airport.