Here's a breakdown:
* אהב (ahev) is the root verb, meaning "to love."
* אהבה (ahava) is the noun form of the verb, meaning "love."
This root is used in many other Hebrew words related to love, such as:
* אוהב (ohev) - lover
* אהובה (ahuva) - beloved
* אהבה (ahava) - love
* אהוב (ahov) - loved