A representative office is a local representation of a company in a foreign country. In most cases it is relatively easy to set up, but a representative office can not conduct any commercial sales or investment transactions. It can be used for market research, business development and marketing, where the parent company will do close the agreements and will be responsible for the delivery. Different countries have different regulations for representative office, especially where it comes to hiring staff.
If you don’t need to do investments in a country, and you just want to sell your products there, it may not be needed to set up a representative office. You can also work with an agent or distributor, or sell directly from abroad.