Domain checked - blacklist help

I am buying a domain and I have run a test in a tool called MX Toolbox and it has come up with 1 blacklist result?

The part that come up yes for blacklist was: dnsbl.spfbl.de (no idea what this is lol)!

Firstly, can anyone explain what this means and if buying this domain can it be fixed.

Someone told me the DNS server can be fixed but I’m unsure why it can (or maybe it can’t and will cause issues down the line)?

Thanks

That is spam traffic related list.

Maybe email but more likely domain was part of DDOS network.