The bridge has washed out and your agent needs to rebuild it before you can keep going!
The bridge is 21 blocks long and 6 blocks wide.
You need to figure out how many blocks you need and make sure the agent has enough dark oak planks.
Make use of the repeat block.
Although there are many ways you can code this so that the bridge will work, this diagram shows the number of each block you will need to create a common solution.
5 - Repeat [ ] times
1 - agent turn left
1 - agent turn right
2 - agent place down
2 - agent set block or item [dark oak planks] count [ ] in slot 1
1 - on chat command "bridge"
4 - agent move forward by [ ]