# No razor will be used upon his head

"No one should ever cut his hair". The angel of the Lord prophesied about Samson and gave instructions to Samson's mother, who was to offer up her son under a Nazarite vow. This was a special type of vow, dedicating Samson to Yahweh. Part of this vow prohibited the cutting of the person's hair.
 
# razor

a sharp knife used to cut hair close to the skin

# a Nazirite to God

"a Nazirite devoted to God" or "devoted to God as a Nazirite"

# from the womb

"from before he is born" 

# the hand of the Philistines

"the control of the Philistines"