Hey, OBV is on-balance volume indicator / oscillator. It's a technical indicator that draws a correlation between an asset's volume and it's price and is very helpful in understanding it's momentum. Basically what you look out for are divergences between the oscillator and the price action when the price is at a support or resistance level. The ichimoku tells us that the kijun sen (the red line) is a point of support/resistance and thus it's a good point to use the OBV. Check out this link, its got a cheat sheet to help you catch the divergence and parse it's meaning : https://www.babypips.com/learn/forex/divergence-cheat-sheet

I hope this helps. We'll know tomorrow if my OBV reading is right! fingers crossed!