The FAQ section at the support website covers this: https://support.dfinity.org/hc/en-us/articles/4489411106324-What-is-required-for-a-vote-to-pass-.
Alternatively, the ICP dashboard shows the same info right below the voting results of any NNS/SNS proposals - note the small info icons next to Absolute Majority and Simple Majority, e.g. OpenChat Proposal: 458 - ICP Dashboard.
Note that voting works in a similar way in NNS and SNS. SNS allows for a bit more configuration, e.g. voting period duration. We’re currently working on increasing some acceptance thresholds in SNS which might be another difference - details here.