One thing we might learn about love from Shakespeare's play is that there are many differenty levels to the act of love. First, there is Shylock who at first appears to love his daughter. However, when she shames him by running away with a Christian, Shylock's love for Jessica is quickly stripped away, even more so when he discovers that she has taken his money with him. At this point, readers might question which Shylock loves more: his daughter or his money.
Bassanio's love is also rather shallow. He claims love for Antonio, but one wonders if this too is based on money. After all, Antonio lends Bassanio money whenever he asks for it. Bassanio's initial attraction to Portia is also based on money. Whether he overcomes this is not quite clear, as Bassanio's commitment to his love of her comes in question when he gives away the ring that Portia has given him.
Portia's love goes a bit deeper. First, she goes to a lot of trouble to save Antonio, based merely on Bassanio's friendship for Antonio. Then Portia forgives Bassanio's transgression over the ring, despite the fact that he failed her test of his love.
However, the deepest love portrayed might be that of Portia's father, who even in death made arrangements to find the most worthy of suitors for his daughter. Whether the king's plan succeeded or failed is immaterial. His love for his daughter was so important, he created a plan that he thought would work.
Well, there's what Shakespeare shows about love, and there's what we learn from it. You might learn something very different, and you'll want to reflect on what he shows us.
That said, I'll gladly share a few thoughts about what Shakespeare shows us about love in this play.
First of all, he shows us that love is interwoven with other drives and desires. (Think of Bassanio's desire to marry Portia in part for her money.)
Second, Shakespeare shows us that there is an element of randomness to love, and that it is in part a game. (Think of the challenge of the caskets.)
Third, Shakespeare shows us that love carries risk. (This would be the whole "pound of flesh" deal.)
Finally, Shakespeare shows us that true love survives through all tests and trials, and finds a way.