If you're reprimanded, someone in authority speaks to you in an angry way because you've done something wrong. Or you might reprimand your dog if he steals your hot dog.
The House of Representatives has a couple of ways to punish naughty members. One way is to reprimand them by voting to express disapproval. In 2009, Representative Joe Wilson was reprimanded after his outburst of "You lie!" during President Obama's speech. In the halls of Congress, this is considered "unparliamentary language," but if you yell at your congressman, that's okay.