Gods. The masculine. Yang. A few common ideas come to mind when we bring up God.
We could even bring up Christianity. However, “God” means something different to every person. Even in Christianity. Some Christians will see their God as all-forgiving while others will see God as unforgiving and bringing down the wrath of the heavens. Pagans are no different. Some will honor Cernunnos and some will honor Odin. Some (similar to me) will honor the masculine that we feel in the Universe and not really be able to give it a name, but will honor different aspects of the Masculine by using different Gods (Odin, Hermes, Thoth, Quetzalcoatl).
Pantheons may not have completely matching Gods, but most of them will have similar God archetypes: Father, Trickster, Warrior, etc. For magickal purposes, when a certain aspect is required, it is easier to use a certain God as a focal point.
Now, not all the traits associated with Gods are considered Masculine by everyone. This is also something that will vary from person to person. And it is totally ok. Go with your gut feeling. If you feel you need a Warrior Goddess, then do so. If you feel you need a Nurturing God, then do so. The person who best knows what you require is you.