It's not 'in code' as such but it relates to how you interact with other applications - to use 'Early Binding' you set a reference using the Tools/References menu and declare variables using syntax like
Late binding is different, you're working with generic 'objects'
You need to decide which is most appropriate for your situation, especially if the workbook is distributed to other users so you need to understand the differences and implications. Best done with a little studying. Any generic search ("vba binding late vs early") will get you all the information you need.
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