Romeo and Juliet the prologue

Two lovers are born from the families. Their love is doomed  by fate because of their birth to warring families.

'Star-crossed' is the phrase that implies  fate. The stars, or fates, are against the lovers from the start, as if their astrology  dooms them.

"Take their life" can be read two ways to take life from (or be born), or to take life away from (or kill). The prologue gives you a hint about how this play will end, with the lovers taking their own lives.  "Take their life" means, on the surface, that these two children gain life from their mothers. However since we know that both Romeo and Juliet commit suicide, the phrase "Take their lives" has a double meaning that forshadows later events. 

• The prologue is a sonnet with 14 lines of iambic pentameter in an ABABCDCDEEEFGG rhyme scheme
• It sets the scene for the play by hinting at most of the action to come
• It describes the setting and basic conflict in the first stanza of four lines 
• The next four-line stanza describes the young lovers and their dilemma 
• The third stanza tells us the family feud will finally end in tragedy, and explains the focus of the play
• The last two lines remind the audience that there is more to come when the play is acted onstage.
• The familes grudges will erupt in bloodshed  and stain  their hands
  

Two families, both equally respected,

Capulets and Montagues equally in rank within the city of Verona. In that period of the play a "household" might include extended family. Both families make up a large population of a smaller town. 

In fair Verona, where we lay our scene,

In the pleasant city of Verona, where this play will take place. 

From ancient grudge break to mutiny,

An old grudge and simmering resentment between the two families will burst into new violence.

The Capulets and the Montagues have a long standing feud that affects everyone in town. The families have not had an erupted feud for a while however the play starts off with them in a brawl indicating this will go further and there is more to come.