Could i get help with GetChildren() please?

a = game.Workspace:GetChildren()
for i = 1, #a do
    if (a[i].className == "Part") then
        a[i].Reflectance = 1
    else return end
end

• All ROBLOX instances within the service (workspace) are returned in a list, which is assigned to a. a then becomes a table containing the list.

• the length operator (#) on the second line followed by a table returns an integer that represents just the index of the last value of the table. In other words, the total number of values in said table.

• a[i] just simply means accessing the value located at index i of table a. Since all values have a unique corresponding index, and that indices are integers, we can only get the value using the index -- because we want the value, and not the number.

For a much easier understanding of how it all works, here's a little cleaner version of the snippet you've provided.

list = workspace:GetChildren()

for index = 1, #list do 
    if list[index].className == "Part" then
        -- if value at index is a "Part" then
        -- set its reflectance to "1"
        list[index].Reflectance = 1
    else
        return
    end
end

Using the call "GetChildren()" is simple. It says what it does. It literally finds and gets the childs of a Parent. You can have an argument in it, or leave it blank. Here is an example:

game.Workspace:GetChildren()