# has made us a kingdom, priests
"has set us apart and begun to rule over us and he has made us priests"
# Father
This refers to God the Father. It is best to translate “Father” with the same word that your language uses to refer to a human father.
# to him be the glory and the power
This is a wish or prayer. Possible meanings are 1) "May people honor his glory and power" or 2) "May he have glory and power." John prays that Jesus Christ will be honored and will be able to rule completely over everyone and everything.