How Can I Find Items In A Variable Like This?

Those are called Tables, you can get values from them by indexing them, in your case you would do this

local names = {"a","b","c","d"}

names[1] -- a
names[2] -- b
names[4] -- d
names[5] -- nil

There is also a different type of values with keys instead of numbers, these types of tables look somehow like this

local SomeTable = {
    ['cat'] = 'something',
    ['john'] = 500,
    'a',
    'b',
    ['c'] = Instance.new('Part'),
    [Enum.NormalId.Top] = true,
}

SomeTable['cat'] -- something
SomeTable[Enum.NormaId.Top] -- true
SomeTable[2] -- b

You see values without index (In your case a, b, c and d, all of them) must be indexed with number which is called Index and refers to location of the element in the table.

Tables Tables Tables Tables