BPO stands for "Business Process Outsourcing," which is simply another term for outsourcing. This is when a company contracts an outside provider for services or business processes. This might include manufacturing or back-office functions such as data entry, data processing, credit card processing, accounting and human resources. But BPO might also includes front-end services such as customer care and technical support.
"Global BPO" is another term for offshoring or outsourcing outside a company's home country or primary market.