What is this canister at the top of a utility pole?

It's a distribution transformer, aka 'pole pig'. It lowers the voltage from the higher voltage in the supply lines to the power used in your house. The distribution lines that run down your street are probably 5-15kV. From the length of the insulators, probably towards the higher end of that spectrum. They contain a transformer and oil used for cooling (in earlier days that oil would contain hazardous PCBs - PolyChlorinated Biphenyls, not printed circuit boards, though I do have a warning sticker on my computer that says it contains PCBs).

Since Costa Rica uses 120VAC/60Hz the secondary voltage probably is center-tapped 240VAC 60Hz as used in Canada and the US.

At a higher level in the distribution food chain, the electricity is all 3-phase but it's common to only distribute the 3-phase along major thoroughfares and then bring a single phase down a smaller street.

These are quite common in North America - in rural and in suburban environments. Only in major cities where the utilities are kept underground are they not seen.

Edit: The IC is probably part of the ICE logo (Instituto Costarricense de Electricidad), the state-run electricity (and telecom) company.

The large grey cannister is a transformer lowering the high voltage from the long distance power line into the voltage you use at home. Most probably you have 110 /220 V ac. if you are in the USA. The other element with glass is your street lightfixture. If you follow the 3 thick wires comming from the transformer they will go to your house connection. Such socalled pole transformers are widely spread in many countries in the world. In western Europe however you hardly find them because there most house connections are under the ground. The transformers are there placed in little stations. Now we are to it accros the insulator as mentioned in the other answer you find mostly high voltage fuses. They are there to disconnect the transformer from the High voltage supply in case something goes wrong. They also enable the technicians to disconnect the transformer from the supply if work needs to be done.

There is a transformer (voltage converter), some insulators, and a lamp.