You may see lots of acronyms being used and they may be confusing at first. Here's a list of some of the more commonly used ones to help you out.
BPOU - Stands for Basic Political Operating Unit, and it's on of the smallest units of political organization. It's the group you'll caucus with early in an election year. It consists of several precincts, but depending on population density it's geographical size can vary. In rural areas it can be a county (or even multiple counties), but in a major metropolis a single city can consist of a number of BPOUs.
CD - Stands for Congressional District, which are determined by the last US Census. Each Congressional District sends one Representative to the US House. It consists of a number of BPOUs, and each BPOU sends delegates to help nominate a candidate. You're currently at the website for the Minnesota Congressional District Two Republicans.
HD - Stands for House District. Each House District sends one Representative to the Minnesota Legislature. Two House Districts make up one Senate District.
PCR - Stands for Political Contribution Refund, and is a program run by the state of Minnesota. Basically you can contribute money to a political party and/or candidate and the state will refund all or a portion of that contribution.
RNC - Stands for Republican National Committee and is the national governing body of the Republican Party.
RPM - Stands for Republican Party of Minnesota, and is the state governing body of the Minnesota Republican Party.
SD -Stands for Senate District. Each Senate District sends one Senator to the Minnesota Legislature.