Angels can communicate with humans in several different ways:
Angels are mighty creatures who have abilities beyond what humans have:
Take heed that ye despise not one of these little ones; for I say unto you, that in heaven their angels do always behold the face of my Father which is in heaven..
A second one, which seems to be aimed at believers in general, is at Hebrews 1:14 as shown
Are they not all ministering spirits, sent forth to minister for them who shall be heirs of salvation.
Others can be found at Exodus 23:20, Psalms 34:7, Psalms 91:11.
Do these passages mean there are angels assigned to each of us to protect us from harm? Only to a certain extent. Realize that these Bible passages specify protection for people who fear God -- not just anyone. This is supported in Genesis 19:1-21 when angels were sent to save Lot from God's wrath on Sodom, and later at Genesis 21:17-19 when an angel was sent to save Ishmael from death in the desert. Much later, an angel was also sent to prevent the Egyptian army from killing the Israelites (Exodus 14:19-20, 24-25). In still another case, an angel was sent to protect three faithful men from burning to death (Daniel 3), and in yet another case, an angel was sent to protect a man from killer lions (Daniel 6:22). It is clear in Scripture: Angels are sent to protect the faithful, not just anyone.
Although God sends angels to protect us, we must realize these angels don't protect us if we are doing something reckless or sinful. For example, if we act recklessly by testing God, we will not be protected (Matthew 4:5-7). If we are sinning and get hurt in the process, we will not be protected (Proverbs 22:8, Galatians 6:7-8, Romans 6:23). The Bible makes it clear that if we make sinful choices, then we deserve the consequences (Proverbs 1:32, 14:12, 16:25).
Therefore, even though angels are assigned to protect faithful believers, they are not assigned to protect us from our own bad judgment or immoral behaviour.
And I fell at his feet to worship him. And he said unto me, "See thou do it not: I am thy fellowservant, and of thy brethren that have the testimony of Jesus: worship God: for the testimony of Jesus is the spirit of prophecy".
and at Revelation 22:8-9
8 And I John saw these things, and heard them. And when I had heard and seen, I fell down to worship before the feet of the angel which shewed me these things. 9 Then saith he unto me, See thou do it not: for I am thy fellowservant, and of thy brethren the prophets, and of them which keep the sayings of this book: worship God.
The prohibition against angel worship is also mentioned at Colossians 2:18, which states:
Let no man beguile you of your reward in a voluntary humility and worshipping of angels, intruding into those things which he hath not seen, vainly puffed up by his fleshly mind
The Bible makes it clear that God is the only one who is to be given worship as shown at Deuteronomy 10:20. This concept is supported in the New Testament at Matthew 4:10:
Then saith Jesus unto him, Get thee hence, Satan: for it is written, Thou shalt worship the Lord thy God, and him only shalt thou serve.
Summing it all up, angels are mighty spiritual entities at God's service, but are not gods to be worshipped. They can manifest their presence in a variety of ways, they possess magnificent powers, and have the choice of free-will. It is a priviledge to experience a close encounter with an angel of God.