Is Glacy a healer?

"Dedicated" is doing real work in that sentence. Aniimo role labels are narrow, and restoring health to team members is the job Glacy is built around rather than a side effect of her kit. Plenty of Aniimo heal without holding the role: Leafy has healing capabilities and still is not classified as a healer. The labels are strict enough that no Fire-type Aniimo fills a dedicated Support role at all, with Flamerion filed as a Fire Regen instead. So when Glacy is called a dedicated healer, that is the classification, not a loose description.

In a fight, that means one of your squad slots is spent on keeping the rest alive. Her healing comes from active skills, and active skills run on cooldowns and draw from the party's single shared energy pool rather than a personal one. Lean on heals constantly and you are spending energy your damage dealers also want. You still have room to shape her: offensive abilities can be configured freely, and she can carry passive abilities and traits that affect how she performs.

Who else can keep the squad up

Glacy is not your only option, which matters if you would rather build around something else. Gracewing is also a healer, with several attacks that heal the squad as they land. Turbo brings shields alongside healing, so the damage gets blunted before it needs undoing. Glameep's healing scales with maximum HP, which ties its output to how the rest of that creature is built. Lunara heals differently again: her normal attacks consume stacks of Power of the Moon to restore both health and energy, so she feeds the shared pool instead of only draining it.

This also means two healers is a choice rather than a requirement. Note that a healer is not a Support. Support Aniimo are built around buffing allies and providing utility, plus debuffs and other interference against enemies, and that is a separate role from restoring health.

Not settled: The name turns up written both as Glacy and as Glacy for the same dedicated healer, so expect to see either. Her element and the exact list of her healing skills are not pinned down.