ECDSA is an encryption algorithm,
ECDSA is a signature algorithm. SA at the end stands for it too: Elliptic Curve Digital Signature Algorithm.
specifically an asymmetric algorithm which uses two keys which is the private key for encryption and the public key for decryption, this also requires a higher computational power to decrypt the original input.
It takes a higher computational power to reverse the private key to public key operation or compute private key from signature.