Exactly, normal RAM for normal PCs. You can use this tool to read out what kind of RAM is already in the PC (select ZIP English), then you will see exactly: https://www.cpuid.com/softwares/cpu-z.html

Do the maths 2x 8GB = 16GB yes are 16GB ;-)

According to the manufacturer, this RAM is compatible with the Asrock h110m-hdv r3.0. Herstellerseite: https://www.gskill.com/qvl/165/185/1534752219/F4-2133C15S-16GIS-Qvl

Yes you are right: DDR4-2400MHz CL15-15-35 1.20V 8GB (2x4GB)