Sometimes it means: US lend $1 billion check to Pakistan at some rate. But Pakistan must buy US weapon for these money, must hire US consultants to use it for its own money, at prices set by US, do this-and-this on the borders, arrest such and such people and so on.
Usually the agreement is not so blatant, but they are only plans. Reality is much worse. I had once seen the ways of Humanity Help from Germany to Germans in USSR in 1990. All money went to local authorities in places where USSR Germans lived and to the civil servants from Germany. The sum was about $200 mill. Not a single normal citizen got anything. I was acquainted with one factory owner from Germany who was outraged with this situation (he gave a large sum in this help fund personally) and promised me ( I was in the counsil of the Moscow German Society then) to do something or at least to get some info or raise a scandal. Result=0.
The corruption in the world is on such level, that I am afraid, sums under 1000 mill. simply disappear in the pockets of the civil servants on both sides. While returning the Russian debt to Czechs in 2001 2/3 of it ($1200mill) disappeared. Officially.
Of course, while it is known, that all the aid will be stolen, the giver could demand something on the civil servants of the state-taker. And somethin will be get. But not much. They love to steal, but they hate to pay.