What does this mean?

[huhmzah]

A friend of mine wanted to know what this meant -- I'm not sure but it seemed like esperanto to me, so if it is, could someone tell me what:
"malrapida komence, sed ĝi laŭgrade akceliĝas kaj post iu sojla momento iĝas rapidega" means
And in particular she wanted to know what "sojla" meant.

[Almar]

Hey.

This means "slow at the beginning, but it gradually accelerated and after some ? moment became really fast".

I don't know what sojla means and can't find a translation anywhere.

[pasalupo]

The meaning of 'sojlo' is threshold. I think in the given context you could translate it as 'moment of transition'.