This is a normal gate into a field. But behind the left pillar there is another large stone. This is an ogham stone.
Ogham is the earliest form of writing in Ireland, it dates to around 4th century A.D. and was in use for around 500 years. The Ogham alphabet is made up of a series of strokes along or across a line. Ogham is sometimes referred to as the "Celtic Tree Alphabet" as a number of the letters are linked to old Irish names for certain trees. The alphabet was carved on standing stones to commemorate someone, using the edge of the stone as the centre line. They normally read from the left hand side bottom up, across the top and if need be down the other side.
Note: There is no need to enter the field in order to retrieve. BYOP.