What does « To push / To defend » mean in the Quran?

So they defeated them by permission of Allah, and David killed Goliath, and Allah gave him the kingship and prophethood and taught him from that which He willed. And if it were not for Allah checking [some] people by means of others, the earth would have been corrupted, but Allah is full of bounty to the worlds.

And that He might make evident those who are hypocrites. For it was said to them, "Come, fight in the way of Allah or [at least] defend." They said, "If we had known [there would be] fighting, we would have followed you." They were nearer to disbelief that day than to faith, saying with their mouths what was not in their hearts. And Allah is most Knowing of what they conceal -

And test the orphans [in their abilities] until they reach marriageable age. Then if you perceive in them sound judgement, release their property to them. And do not consume it excessively and quickly, [anticipating] that they will grow up. And whoever, [when acting as guardian], is self-sufficient should refrain [from taking a fee]; and whoever is poor - let him take according to what is acceptable. Then when you release their property to them, bring witnesses upon them. And sufficient is Allah as Accountant.

Indeed, Allah defends those who have believed. Indeed, Allah does not like everyone treacherous and ungrateful.

[They are] those who have been evicted from their homes without right - only because they say, "Our Lord is Allah." And were it not that Allah checks the people, some by means of others, there would have been demolished monasteries, churches, synagogues, and mosques in which the name of Allah is much mentioned. And Allah will surely support those who support Him. Indeed, Allah is Powerful and Exalted in Might.