Freeview is the 'brand' name for digital terrestrial television in the UK. In your case it means that the television set has a built in tuner capable of receiving digital broadcasts without the need for a separate freeview box.
The television may also have a conventional built in analogue tuner too. If this is the case then when you switch it on for the first time and do the setting up you should make sure that you tune in analogue channels as well as digital (Freeview) ones. It is important that you read the instructions carefully - as many times as necessary - until you understand how to set the tv up properly.
The digital (Freeview) service includes the standard BBC1&2, ITV1, Ch4, Ch5 channels and about 40 others, plus dozens of digital radio stations. Most of the Freeview tv channels only broadcast part-time so you won't have a choice of dozens of tv programmes running simultaneously. The digital tv propaganda is a bit naughty in that respect.
I don't know what the status of digital terrestrial broadcasting is in Ireland, it may be different from Britain (where everywhere will be digital by the end of 2012).
Be aware that Freeview reception needs a good aerial or you lose channels and get bad pictures.
If you only have an indoor one then be prepared to replace it with a nice big outdoor one. If you have to buy a new aerial please note that there is no such thing as a "digital aerial". Some shops (and aerial makers) say that there is, and try to charge more money for it. All you need is the biggest (most horizontal elements) television aerial that you can fit onto your roof. Normally a 36 element aerial is more than good enough.