An account on the Aave V3 Pool on Arbitrum supplies and borrows any of its reserves under one health factor, so each bar adds every reserve in USD, each flow at Aave's oracle price for its reserve at its block. The collateral bar adds up to what the account holds: supplied and the interest earned, less what was withdrawn. The debt bar adds up to what it owes: borrowed and the interest accrued, less what was repaid.

Interest is the dashed part. Every row states its reserve's balance just before and after it, as the aToken and the variable debt token held it at that block. So the interest between two rows of a reserve is the balance just before the later one less the balance after the earlier one. Between events each balance grows at the rate the rows imply, in a straight line from one row to the next; after the last row, to the Pool's balance today. That growth and the change in prices since each flow are the last line of each bar, Market move and interest since the last event. The Pool rounds each balance to its token's smallest unit, so an act can move a balance a unit or two more or less than its amount; that rounding sits in the same line.