N Seconds

I am having problems getting a grip on what the N means?

In the example below the author is describing cache and he is also incuding in the example that N that i do not understand.

Any help would be great!

Thanks ahead of time.


Note that with inserting items into the Data Cache using the Cache(key) = value method or the Cache.Insert(key, value) we have no control over when (if ever) the items are evicted from the cache. However, there are times when we'd like to have control over when items leave the cache. For example, perhaps we want to have an inserted item in the cache to only live for n seconds, as with Output Caching. Or perhaps we'd like to have it exit the cache n seconds after it's last accessed. With Data Caching, you can optionally specify when the cache should have a member evicted.