SignWriting has hundreds of symbols, far more than the twenty-six symbols (A to Z) of the Latin alphabet.
There are two reasons for this. First, sign language itself uses hundreds of handshapes and movements, and SignWriting needs enough symbols to write them all.
Second, different sign languages use different handshapes and movements, and SignWriting needs enough symbols to write all known sign languages, and not just one or two of them.
While the large number of symbols makes SignWriting seem difficult to learn, note that the symbols are iconic – they look like the handshapes and movements they represent. This makes them easier to learn, even though there are so many of them.