"Tang" means "in vain". Therefore, it can be interpreted as "all the merits and efforts in the world will not be paid in vain, but will be rewarded."
"Tang donation" is a word in Buddhist scriptures, which means destroyed and wasted. A person's efforts will take root, blossom and bear fruit in an invisible and unexpected place.
Extended data:
Hokkekyo Avalokitesvara Bodhisattva: "If all sentient beings respectfully worship Avalokitesvara, they will not give, so all sentient beings deserve the name of Avalokitesvara." Later generations gradually wrote the sentence "Fu didn't donate to the Tang Dynasty", which expanded the "Fu" simply referred to in the scriptures to "Gong" that can refer to all endeavors.
Basic explanation
Everything in the world is dominated and driven by cause and effect. Rise and fall, rise and fall, strength and weakness are not accidental, and they can't escape the law of cause and effect. People's suffering today is just the result of various evil causes. If people want to get good results in the future, they must work hard to cultivate good careers now. When planting good causes, we should realize that success is not necessarily in me, but efforts must not be donations. Accidentally, the blessings will be cashed one by one sooner or later, but the time has not yet arrived.
References:
Baidu Encyclopedia-Free Donation