That's usually a football term, and often coaches who are bad at it can lose a game in the crucial moments because they don't manage their timeouts corrctly.
But it's very important in the news business as well, touching everything from the length of your packages to managing your time during the day to letting Presidential candidates run over their allotted time as you channel Clint Eastwood's empty chair as moderator. (Memo to CNN's Candy Crowley: Will you please, please, please control tomorrow night's debate? The last two reminded me of those days when we ran roughshod over substitute teachers.)
Back to that clock. One of the more common concerns I hear from people in smaller markets is the package length question. They're worried that their packages are too long, that a two-minute piece will be dismissed because they're applying to stations that demand nothing longer than a minute-fifteen. Or they're worried they won't be able to cut down the time to what will be the standard at the next job.
Let's deal with the first part: News Directors in bigger markets know that packages often run longer in smaller ones. They know you've got limited resources, a small staff and often few stories to fill the allotted time. So they're not going to eject your tape simply because your package runs a little long.
As for learning to cut down your time when you get to that new job, you might start doing that now. Take some of your scripts home tonight and look at them. Are there extraneous words you could do without? Too many sound bites that say the same thing, or soundbites that are too long? Too much voiceover stating the obvious? Could you have used two seconds of nat sound to convey the setting instead of two sentences?
Personally, I love longer stories that let the package breathe. But many NDs are obsessed with story count and package length, so you have to give them what they want. Best to learn how to do it in case you have to comply with those standards.