What do you mean by onus probandi?

Excuse me, but could you please clarify what you mean by the term "onus probandi"? It seems to be a legal term that I'm not entirely familiar with. In the context of cryptocurrency and finance, is it related to the burden of proof in disputes or investigations involving digital assets? Is it something that investors, traders, or exchanges need to be aware of? I'd appreciate it if you could elaborate on its meaning and any potential implications it may have in the world of cryptocurrency and finance.