जो केक दुकानदार ने बनाया, उसका आकार बड़ा है।

to be

Breakdown of जो केक दुकानदार ने बनाया, उसका आकार बड़ा है।

• बड़ा: big
• बनाना: to make
• केक: cake

Questions & Answers about जो केक दुकानदार ने बनाया, उसका आकार बड़ा है।

What is the जो ... उसका ... pattern doing here?

This is a very common Hindi relative-correlative structure.

• जो केक दुकानदार ne बनाया = the cake that the shopkeeper made
• उसका आकार बड़ा है = its size/shape is big

Hindi often uses a two-part pattern like this instead of packing everything into one English-style relative clause. So literally it feels like:

The cake which the shopkeeper made — its size is big.

That is a normal Hindi way to connect the two ideas.

Why is ने used after दुकानदार?

ने is the ergative marker. In standard Hindi, it is commonly used with the subject of a transitive verb in the perfective.

Here:

• verb: बनाया = made
• base verb: बनाना = to make
• this is a transitive action, and it is in the perfective

So Hindi says:

• दुकानदार ने बनाया = the shopkeeper made

Compare:

• दukानदार केक बनाता है = The shopkeeper makes cakes / is making a cake depending on context
  → no ने
• दुकानदार ने केक बनाया = The shopkeeper made the cake
  → ने appears

How do I know that the made the cake, and not the other way around?