What it means by being in 'ibadhah?

(25:63)The (true) servants (or )the men in 'ibadhah ,of the Merciful are those who walk humbly on the earth who, when the ignorant people behave insolently towards them, say,"Peace unto you"
(25:64) who pass their nights in prostrating themselves and standing before their Lord:
(25:65)who pray, "Our Lord, save us from the torment of Hell, for its torment is killing:
(25:66) it is an evil abode and an evil resting place"
(25:67)who, when they spend, are neither extravagant nor miserly but keep the golden mean between the two (extremes):
(25:68)who do not invoke any god but Allah nor kill a soul, which Allah has forbidden, unjustly, nor commit adultery. -He who does this shall be punished for his sin,
(25:69)and his torment shall be doubled on the Day of Resurrection, and he shall abide in a state of ignominy
(25:70)except the one who may have repented (after those sins) and have believed and done righteous works, for then Allah will change his evil deeds into good deeds, and He is very Forgiving and Merciful.
(25:71) In fact, the one who repents and does righteous deeds, returns to Allah as one ightly should.
(25:72)(And the servants of the Merciful are those:) who do not bear witness to falsehood and who; if they have ever to pass by what is vain, pass by like dignified people:
(25:73) who do not behave like the blind and the deaf, when the Revelations of their Lord are recited to them for admonition
(25:74) who pray, "Our Lord, bless us with wives and children, who may be the comfort of our eyes , and make us leaders of the righteous. "
(25:75)Such are the people who will be rewarded with high palaces for their fortitude, wherein they will be welcomed with due respect, honour and salutations