It is unclear which are their goals but this is the first such land intervention by the Zionist Colony in the Gaza Strip since they evacuated it in 2005.
It is however apparent that the Zionist State is probably behind the offshore gas wealth of Gaza, already controlled de facto by the Zionists but legally disputed by the UN-recognized Palestine State, and it may well also attempt a throughout genocide in the massive open air prison, forcing the exit of most of its 1.7 million denizens (mostly refugees from other parts of Palestine, now annexed to "Israel") to Egypt or even kill them on the spot with chemical weapons, which are known to have been used already in the few hours that the attack has lasted.
The Zionist campaign seems dead set into occupying all Gaza and has absolutely no qualms about murdering civilians, including children and the infirm.
My understanding is that they want to implement a massive genocide in all the residual Palestine and that this Gaza "campaign" is just the beginning. The very convenient presence of the so-called Islamic State in neighboring areas and the firm pro-Imperial grip of the Military Junta in Egypt make it impossible that anyone seriously challenges the Zionist genocidal campaign so they are quite probably attempting to kill or expel all Palestinians still living in their homeland in a new edition of the 1948 Nakba.
If the Zionist State succeeds in Gaza, next will be the West Bank and Galilee, where the Native Palestinian population is still dominant. Dissident "Israelis" are also being targeted by Jewish Superiority Nazi mobs, which have been unleashed through much of the suffering country of Palestine.
Meanwhile the Zionist allies in Europe and North America just look elsewhere and pretend this is just a "war" with a particularly uncomfortable high civilian death toll.