What exactly is a BT Romania ETF?

It is an ETF (Exchange-Traded Fund), an investment fund that trades on the stock exchange. 

Think of it like a shopping cart. Instead of buying a single product, you buy the whole basket—that is, multiple shares in a single transaction. The BT Index Romania ETF tracks the BET TR index, which includes the most important companies on the Romanian stock exchange, such as Banca Transilvania, OMV Petrom, Hidroelectrica, and others. You buy one unit of the ETF, and automatically, you invest in all of them.