When you're talking about how long something has been going on, it's common to talk about "round" numbers like one year, five years, 6 months, ten days, two hours, etc. When the time that's passed has almost reached one of those round numbers, but not quite, use "nearly":
We've been married for nearly ten years.
This one is nearly a month old, believe it or not.
"Nearly" is very similar to "almost", and they can be used interchangeably in most situations.