Isa is the vowel sound ee (a long e like seize)
Anglo-Saxon Rune Poem (from ragweedforge.com)
Ice is very cold and immeasurably slippery;
it glistens as clear as glass and most like to gems;it is a floor wrought by the frost, fair to look upon
Isa means Ice. That is probably the most consistent rune in the all the Futharks, as it means ice in virtually all of them. The Anglo-Saxon stanza refers to the beautiful quality of ice, although it does give a brief indication of its dangers (cold and slippery).
Esoterically, it is cold, frozen, slippery, yet also static and unchanging. Things that are frozen at very low tempatures, don’t decay or change. That is why we have modern day freezers, to help us preserver our foodstuffs longer, because as long as they are frozen, they won’t decay as quickly. With Isa, you can freeze energies, entities or whatever, stopping them from reaching you. You can also use it to freeze yourself, giving time to reflect, be still and calm. Eventually though, things will thaw and when the ice melts, it can bring a gentle renewal or a mighty flood.
In a quite literal interpretation for the month of February, I think winter will hold on a bit longer then normal. But that is just my hypothesis. Also, don’t expect a great deal of change in this month, which can be both good and bad. Everything will probably just seem to take extra effort, unless you apply some heat to get things moving along.