What does this common utility code do? (BeLazyOnFileOpen)

[ColinKennedy]

I see this in a number of repositories on GitHub but haven't found an explanation yet on what it does. It's found in GitHub almost 200 times to date - https://github.com/search?q=BeLazyOnFileOpen&type=code

local module = {}

module.lazy_load = function(plugin)
  vim.api.nvim_create_autocmd({ "BufRead", "BufWinEnter", "BufNewFile" }, {
    group = vim.api.nvim_create_augroup("BeLazyOnFileOpen" .. plugin, {}),
    callback = function()
      local file = vim.fn.expand "%"
      local condition = file ~= "NvimTree_1" and file ~= "[lazy]" and file ~= ""

      if condition then
        vim.api.nvim_del_augroup_by_name("BeLazyOnFileOpen" .. plugin)

        -- dont defer for treesitter as it will show slow highlighting
        -- This deferring only happens only when we do "nvim filename"
        if plugin ~= "nvim-treesitter" then
          vim.schedule(function()
            require("lazy").load { plugins = plugin }

            if plugin == "nvim-lspconfig" then
              vim.cmd "silent! do FileType"
            end
          end)
        else
          require("lazy").load { plugins = plugin }
        end
      end
    end,
  })
end

return module

What is this? Is it basically something like "it is basically VeryLazy but it runs on-file-open instead of on Vim's startup" - something like that?