From an article in Eurocode standards (https://www.eurocode.us/earthquake-resistance-eurocode-8/imp...

"Clause 5.2.3.3(2) The design value of the flexural capacity of a beam in negative (hogging) bending may be where Asl and As2 (Asl >As2) are the cross-sectional areas of the top and bottom reinforcement, respectively..."

"...the increased flexural capacity of the beam in negative (hogging) bending due to slab reinforcement which is parallel to the beam..."

Negative bending (also called hogging) is when a bending moment bends a beam concave downward (like a sad mouth) and positive bending is when a bending moment bends a beam concave downward (like a smiley mouth). Flexural capacity is also called flexural strength, bending capacity and bend capacity.

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Note added at 15 hrs (2020-10-03 16:51:38 GMT)
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The sentence should say "Negative bending (also called hogging) is when a bending moment bends a beam concave downward (like a sad mouth) and positive bending is when a bending moment bends a beam concave upwards (like a smiley mouth). Flexural capacity is also called flexural strength, bending capacity and bend capacity.