Their goal is.. complicated. First you have to realize that the 'coalition' currently in power in Israel, headed by Netenyahu's
Likud party, represent the more right-wing, hardcore section of Israeli politics. Bibi is a well-known hardliner; he has argued for decades for less negotiation and more military action. His right-wing war rhetoric is largely believed to have played a role in the assassination of Israeli PM Yitzhak Rabin in 1995 by Jewish extremists due to his perceived 'complacency' and softer tone with Palestine.
Like most hardliners Bibi's policies are directed towards keeping Palestine 'subdued'; they believe (with some merit) that allowing Palestine to become a strong, independent and more developed nation is the worst possible thing that could happen for Israel, and so his policies reflect this notion by focusing on curtailing Palestinian attempts to develop. He was, for example,
extremely against any attempt by Palestine to go the UN; he was totally against Fatah and Hamas normalizing relations; and he unashamedly threatened action against Palestine in both these instances.
This is what led to this war. When the three teenaged Israelis were kidnapped and killed in the West Bank, he immediately pounced on the opportunity to launch a massive, pre-planned and unprovoked military assault against Hamas. Despite the fact that Israeli intelligence knew within the first day or two that the teenagers were dead, this information was suppressed, and he used the excuse of trying to find the teenagers -- and that Hamas was directly responsible -- in order to justify this massive campaign of arrests and systematic destruction of Hamas in the West Bank. Only later did it become known that the teenagers were dead from the beginning, and that Hamas wasn't responsible.
It's important to note that this assault came
less than a month after Fatah and Hamas officially formed their Unity government, headed by Fatah and Mahmoud Abbas and containing a minority number of Hamas political officials (many of whom were detained in the sweep). The campaign effectively destroyed the Palestinian Unity government by detaining most Hamas ministers and government officials.
As this occured, Hamas threatened retaliation. And rightfully so. The Israeli government manipulated the tragedy of three murdered kids to justify an attack that was 100% politically motivated. Israel ignored the warnings, and continued with their assault, eventually rounding up somewhere around 500 people, most of whom were placed in "administrative detention" -- the term for holding dangerous suspects without trial, charges or due process, for indefinite periods.
It seems fairly certain that Bibi and his generals orchestrated this entire war as a coup de grace against Hamas. Every step of this war has been a result of Israeli provocation and escalation. First launching a massive detention campaign, then a massive aerial bombardment, and then a ground invasion.
The 'goal' of their invasion is twofold. First, to destroy Hamas. Second, to punish Palestinians for their perceived "guilt" in allowing Hamas to exist. This is called the
Dahiya doctrine. It is essentially a policy where
Israel will now officially hold the civilian populations of their enemies responsible for the existence of said enemies. This is why you are seeing hospitals, power plants, schools, universities, civil infrastructure and the like, along with entire neighbourhoods, destroyed -- they are purposely targeting the civilian population of Gaza for systematic dismantling in order to cause as much suffering and 'backlash' as possible.
It's similar in a way to the policies of nations during WW2, where entire cities became valid targets and millions of people perished in mass carpet bombings.
So there you have it. Israel's goal is to stop being attacked. They have decided -- or rather, the current government of Israel has decided -- that the best way to do this is to literally torture the entire population of Gaza until they submit, and are no longer willing or able to even think about fighting back.