What does it mean to be holy?

Exodus 19:6 HCSB

6 and you will be My kingdom of priests and My holy nation.’ These are the words that you are to say to the Israelites.”

Exodus 20:1–6 HCSB

1 Then God spoke all these words: 2 I am the Lord your God, who brought you out of the land of Egypt, out of the place of slavery. 3 Do not have other gods besides Me. 4 Do not make an idol for yourself, whether in the shape of anything in the heavens above or on the earth below or in the waters under the earth. 5 You must not bow down to them or worship them; for I, the Lord your God, am a jealous God, punishing the children for the fathers’ sin, to the third and fourth generations of those who hate Me, 6 but showing faithful love to a thousand generations of those who love Me and keep My commands.

Leviticus 11:44 HCSB

44 For I am Yahweh your God, so you must consecrate yourselves and be holy because I am holy. You must not defile yourselves by any swarming creature that crawls on the ground.