zi, si,ci, dzi, ni almost always sound like "źi", "śi", "ći", "dźi", "ńi" - that is how soft consonants + "i" work; exceptions are rare and of foreign origin, like cis- if it's a plant is is ćis, if it's a sound it's c-i-s.

Also if zi, si,ci, dzi, ni are before a vovel, "i" just softens the consonant Kasia [Kaśa]

"Moc" is "power", mostly in the electrical meaning. Also "the Force" in Star Wars.