Start process -"Start using Metachain or API"

Dear Experts,

I have a process chain,PC2 that needs to be scheduled after completion of process chain, PC1. Now can I use the condition "Start using Metachain or API". But I have no idea how it works. I referred to documentation service.sap.com but they dont tell me much about this. Can somebody please tell me or refere me to some kind of documentation on how this condition works?

Thanks.