You need to have your Marketing Department running to be able to run advertisement.
Advertisement is product-centric but region-free. As long as you are the top advertiser of a particular product, this product's brand awareness will be effective in all regions.
How It Works
Advertisement is charged daily, and your company must bid to be the top advertiser of a product at time of the advertisement to gain brand awareness.
Auction runs every real-week, which is about six game-months. You should make sure your company has enough budget to pay for the daily cost of advertisement during these six months.
Brand Awareness (BA)
It is just a figure which will be attached to every batch of products being put on the market.
If your company is the top advertiser on a particular day, this BA figure will increase by one point. If your company is not the top advertiser, this BA figure will decrease by 0.1 point (until it reaches zero).
Advertisement improves brand awareness of a product. Some consumers may buy branded products even if they are slightly more expensive.
It is not always necessary to run advertisement if your company is a monopoly, or the market demand is higher than all companies could satisfy.