This is a very interesting Celtic coin from Panonia. Unfortunately I don't know anything else about this coin, so would appreciate any additional info, like the location where it was found and dating.
Front: Solar rider.
I already wrote about the symbolism of the solar rider in my posts "The horseman" and "King John". It is a very common motif on Celtic coins which shows that Celtic religion was in essence a solar cult.
In short, this solar rider represents the sun god. The sun god dominates the white part of the year, the period between Belatane and Samhain, the summer and autumn. You can read more about the Celtic calendar in my post "Two crosses".
Back: Lion's head. In the middle of the white period of the year, at the point that marks the end of summer and the beginning of autumn, we find zodiac sign Leo (lion). The point that marks the end of summer and beginning of autumn, Lughnasadh, falls in the middle of the Leo zodiac sign.
But it gets better.
Why does the lion have fish symbol around his eye?
Have a look at this image:
The point marking end of the Leo (lion) zodiac sign is directly opposite to the point marking the beginning of the Pisces (fish) zodiac sign. The constellation Pisces is invisible during the Pisces period. In the Northern hemisphere Pisces can be seen from August to January, right after the Leo period...
Lion is literally looking at fish...
Such complex zodiac imagery is an interesting thing to find on a Celtic coin don't you think?