Particle marking direct and indirect object, agent, source (indefinite), instrument, causation. To, towards, at, in, on, by, because of, for, due to, by means of.
It's very similar to "ma" which is defined as:
Indefinite locative, instrumental, manner. At, in, on, beside, along, through; by means of, because of, in behalf of, according to. This very common part. is perhaps more specific than the similar i, at, in;
They're often interchangeable, but "i" can give direction (to, towards) unlike "ma." My interpretation of it is that you would use "i" to give a general sense of where something is, like " near the table," but use "ma" to be more specific; "exactly at the table"