'MinPeakProminence' is used when you want to return only those peaks that have a minimum relative importance of the value specified for this argument. Your best resource is the documentation which explains what this Name-Value pair does:
For an example, look through the "Prominence" section in the above link for description of the motivation behind this.
Also, as a reference, see the following example that returns peaks with a prominence of at least 4: https://www.mathworks.com/help/signal/ref/findpeaks.html#buhd30k
