“us” refers to Peter and those Jewish believers who were there in the beginning, but not everyone in the room was there in the beginning. If your language must decide, use the exclusive form. (See: [[rc://en/ta/man/translate/figs-exclusive]])
## in the beginning ##
<b>in the beginning</b> Peter is referring to the day of Pentecost.
## you shall be baptized in the Holy Spirit ##
"God will baptize you in the Holy Spirit" (See: [[rc://en/ta/man/translate/figs-activepassive]])