What is happening here is that Paris is asking again about marrying Juliet. Capulet is willing for them to get married, but not really ready yet.
First he tells Paris that Juliet is too young. He says that she is fourteen and so Paris should wait another two years to marry her.
Paris persists and Capulet tells him that he needs to woo Juliet. He needs to get her to consent to marrying him and then it will be okay with Capulet.
This is in contrast to what will happen later in the play. Capulet will get absolutely enraged when Juliet doesn't want to marry Paris later in the play.
When Paris first asks for Juliet's hand, Capulet is reluctant to agree. His main argument is that Juliet is too young, being not yet 14. Paris argues that younger girls than Juliet get married and have children, but Capulet seems to feel that this can ruin their lives. This is why his change of heart is surprising (at least to me). He tells Paris:
But woo her, gentle Paris, get her heart;
My will to her consent is but a part.
An she agree, within her scope of choice
Lies my consent and fair according voice.
So, if Juliet agrees to love Paris, then Capulet will give the pair his blessing. But Paris has to win over Juliet first. Later in this scene, Romeo & Benvolio encounter a servant of Capulet's, who is supposed to deliver a letter. Unfortunately (well, fortunately for Romeo), this servant cannot read. Romeo reads the letter for him, & finds out that Rosaline will be at the party. Romeo & Benvolio decide to go to the Capulets' party. Benvolio thinks it will be the perfect chance to get Romeo's mind off Rosaline...in that, he promises to show him much prettier girls. Romeo resolves to go, but only to fawn over his love. Little does he know...