Why does the USA gives so much money to Israel every year and gives them weapons? What benefit does Israel give the USA?

Israel is a European colonial project. Historically, it acted as a convenient way for anti-Semitic Europeans to get Jews out of their countries. Over time, it became clear that this could be leveraged to create a European-aligned state that would act as a bulwark against states hostile to Western imperialism in the Middle East, which is one of two reasons why Israel has been hyper-militarized since its foundation (the other reason is the maintenance of its settler project through indigenous displacement, cleansing, and containment).

Israel's early identity was rooted in the idea that its very existence was under grave threat from the Arabic people surrounding it. This is not inaccurate; there was, understandably, enormous hostility to a European settler project in one of the heartlands of the Middle East, and its founding was based on an enormous act of violent displacement (the Nakba) against an Arabic indigenous nation, which had been under brutal British imperial subjugation for a few decades already.

Throughout the Cold War, the Middle East was an enormous region for contest between the two world powers, and the ever-increasing importance of capitalism's most essential commodity, oil, meant there was an increased drive for control and extraction of resources in the region. Though Israel's foundation was orchestrated by the British Empire, it was the US (and in the early days, the USSR) who really propped up and supported the newly formed state, which accurately identified who the new global powers would be post-war.

Because of the intense hostility between Israel and its neighbors, the US and Israel had strong propaganda justification to further entrench Israel's military as a premier power in the region. Israel acts as a constant threat to countries that would resist Western imperialism. It acts essentially as a military base disguised as a country. This tight relationship between the US and Israel was self-reinforcing, and they've only grown closer and closer over time. You could make the argument that no country on earth is more closely aligned to the US than Israel. There are now very strong economic links between the two countries, especially in tech and the military industrial complex (which of course overlap a great deal).

It's also worth noting that most Jews in the world live in the US. Even though support for Zionism is absolutely not universal among Jews, support for it is strong, and so there's a genuine voting base in a number of major urban centers that aggressively pushes for pro-Israel politics. The reasons above are more important, but this shouldn't be neglected entirely.