Another word for kindly beginning with 'b' is benevolent.
Balance
Battery.
bewitched
Pullets Bantams
By gum or bygum which means Wow. Blast!
Break a leg is a phrase that means Good luck. Bite your tongue is a phrase that means Avoid talking.
Botany
bananabacteriabasilicaballerinabelugabandannabarracudabolognabulimia
Bank on it!
backbonebackgroundballparkbaseballbaseboardbasketballbathhousebathtubbathwaterbirdhousebirthdaybirthmarkbirthrightblackbirdblackboardblackmailbloodbathbookmarkbookshelfbluebellbluebirdblueprintboyhoodbrainwavebreadwinnerbreakwaterbrownstonebutterball
clear, not confusing. 100% sure.
A b word meaning helpful is beneficial.