The most beginner friendly support classes are the Bard and the Cleric. The Cleric is a very powerful healer, with their Healing Font feature granting them a number of free extra heal spells per day, and it comes in 2 flavours: The Cloistered Cleric, that wears robes and casts spells, and stays at the back of the party, and the Battle Cleric, that wears armor, uses a shield, and works as a front line class.
Both can do a fair bit of buffing and debuffing with their non-font spell slots.
The Bard is the gold standard support caster in the game, with less focus on healing, and a wider variety of support options.
Clerics have access to the Divine spell list, and are Prepared Casters, while Bards use the Occult spell list, and are Spontaneous Casters. Take a look at those lists, and what those casting types mean, at the Archives of Nethys