To help you better understand Shakespeare's The Merchant of Venice, here is a quick explanation of some of the basic aspects of the text:
The basic plot of the play revolves around the characters Antonio, Bassanio, Shylock, and Portia. Bassanio asks Antonio for financial help in his quest to woo the wealthy Portia, and Antonio secures a loan from the Jewish moneylender Shylock to help Bassanio. Bassanio wins Portia's love, but Antonio gets into money troubles when he can't pay back Shylock's loan, and he faces the prospect of sacrificing a pound of flesh to the moneylender. Portia saves the day when she shows up in disguise to Antonio's trial in Venice and finds a loophole that prevents Shylock from exacting his revenge. The play ends with weddings, restored fortunes, and Shylock's humiliation.
The play is often referred to as one of Shakespeare's "problem plays." In many ways, it can be seen as a comedy in the older sense of the word (there's a happy ending, with the good characters ending the narrative by marrying and seeing their fortunes restored). The play also deals with some pretty serious themes, however, some of which are not fully resolved. The idea of religious conflict and oppression is probably the most significant of these themes. For instance, while Shylock is undoubtedly the villain of the play, he's also written to fit the anti-Semitic stereotypes of Shakespeare's day. Moreover, he's oppressed by the supposed "heroes" of the play, including the theoretically "virtuous" Antonio. As such, Shylock's end can be seen in some ways as tragic, as his vengeful attitude is a result of the oppression he faces at the hands of his Christian neighbors.
In short, while Merchant can be seen as a comedy, it's also wrestling with deeper, darker themes than a classic comedy normally does, and this fact makes it a tough play to understand. If you need more help with the text, check out eNotes' other resources by following the links below.