A treasury bill is short-term government borrowing. The National Bank offers a quantity, banks and institutions bid, and the weighted average yield is the effective interest rate the government ends up paying across the accepted bids.
Bid-to-cover is bids received divided by the amount offered. A high ratio means the auction was heavily oversubscribed, which usually pushes the yield down. Treasury bill yields matter beyond government finance: they are the closest thing Ethiopia has to a risk-free rate, so they anchor pricing across the rest of the market.
Amounts are in birr. Figures come from the National Bank of Ethiopia via the StockMarket.et data hub and are published for information only.