-a 100: This sets the number of iterations for the key derivation function, which increases the amount of time it takes to crack the key. In this case, the parameter is set to 100, which is a higher number than the default value of 16, making it more secure.
-t ed25519: This specifies the type of key to generate. In this case, ed25519 is used, which is a newer and more secure algorithm compared to older algorithms like RSA or DSA.
-f filename: This specifies the filename for the key file. The key file will be saved in the current directory with the name specified after -f. The filename parameter can be replaced with any desired name for the key file.