The caster conjures objects from Gaea’s creative energies.
Casting Time Standard Action
Components Verbal , Somatic or Divine Focus
This spell summons to your side a natural creature (typically an animal, fey, magical beast, outsider with the elemental subtype, or a giant). The summoned ally appears where you designate and acts immediately, on your turn. It attacks your opponents to the best of its ability. If you can communicate with the creature, you can direct it not to attack, to attack particular enemies, or to perform other actions as you command.
A summoned monster cannot summon or otherwise conjure another creature, nor can it use any teleportation or planar travel abilities. Creatures cannot be summoned into an environment that cannot support them. Creatures summoned using this spell cannot use spells or spell-like abilities that duplicate spells that have expensive material components.
When you use a summoning spell to summon a creature with an alignment or elemental subtype, it is a spell of that type. All creatures summoned with this spell without alignment subtypes have an alignment that matches yours, regardless of their usual alignment. Summoning these creatures makes the summoning spell’s type match your alignment.
Pathfinder SRD- Summon Nature’s Ally- http://www.d20pfsrd.com/magic/all-spells/s/summon-natures-ally/