I made an error above, there are 236 numbers not 256. I don´t know if they are meant to be together or not. There is a mix of upper case, lower case, numbers, slashes, plus symbols.
I'm afraid this could be almost anything, in that case.
There are no obvious private key related numbers which are 236 characters long (or some standard fraction thereof). The commonly used base systems in bitcoin - binary, hexadecimal, and Base58Check - do not include slashes or symbols. Most likely, this is an encrypted private key, seed phrase, wallet file, or some other encrypted data.
By any chance are the first characters "U2FsdGVkX1"?