Far left is a thermometer, "thermo" means "heat", "meter" means "measure" (both Greek words). If it gets hotter, what will happen to the blue liquid inside? How will it move? Can you explain why?
Middle is a volumetric flask - note the etched ring on the neck, between the two white lines drawn in. When filled exactly to that ring, the flask contains an exact volume of liquid (2000 ml = 2 liters for the flask shown).
On the right is a hydrometer ("hydro" = water in Greek) - it measures something about water, namely density and buoyancy, which can indirectly tell how much salt is dissolved. Just how that works is coming up next...