"There is frost now."
Translation:Tha reòthadh ann a-nis.
I am still having trouble with that myself. What I do to help is replay the recordings over and over again until you can say the words yourself and make sure you look for patterns in the soundings of the letters. There is also a YouTube channel "Gaelic With Jason" and he has some videos about pronunciation that I found really helpful and you should check it out. https://www.youtube.com/playlist?list=PLFf_f4NNGLdk5t7frEXeJcPSkBF-iEgsV
It is entirely optional in English whether you have a in front of the frost,with very slightly different meanings. That is, the word can be countable or uncountable. Whether they accept both I don't know, but they should.
But it would not be normal to have the there. You would only use the if referring to some specific frost, such as the one that was mentioned on the weather forecast
The frost that they said would come is here now.