Full query for id_shop = 1, id_lang = 1.
You can insert the SQl query into your phpMyAdmin and you will see the result.
The sign column is the + or - sign of the reaction.
So the result is physical_quantity column * sign column.
SELECT SQL_CALC_FOUND_ROWS sm.id_stock_mvt, sm.id_stock, sm.id_order, sm.id_employee, sm.employee_lastname, sm.employee_firstname, sm.physical_quantity, sm.date_add, sm.sign, smrl.id_stock_mvt_reason, smrl.name AS movement_reason, p.id_product AS product_id, COALESCE(pa.id_product_attribute, 0) AS combination_id, IF( LENGTH(COALESCE(pa.reference, "")) = 0, IF(LENGTH(TRIM(p.reference)) > 0, p.reference, "N/A"), CONCAT(p.reference, " ", pa.reference) ) AS product_reference, pl.name AS product_name, p.id_supplier AS supplier_id, COALESCE(s.name, "N/A") AS supplier_name, COALESCE(ic.id_image, 0) AS product_cover_id, (SELECT GROUP_CONCAT( DISTINCT CONCAT(agl.name, " - ", al.name) SEPARATOR ", " ) FROM ps_product_attribute pa2 JOIN ps_product_attribute_combination pac ON ( pac.id_product_attribute = pa2.id_product_attribute ) JOIN ps_attribute a ON ( a.id_attribute = pac.id_attribute ) JOIN ps_attribute_lang al ON ( a.id_attribute = al.id_attribute AND al.id_lang = 1 ) JOIN ps_attribute_group ag ON ( ag.id_attribute_group = a.id_attribute_group ) JOIN ps_attribute_group_lang agl ON ( ag.id_attribute_group = agl.id_attribute_group AND agl.id_lang = 1 ) WHERE pa2.id_product=p.id_product AND pa2.id_product_attribute=pa.id_product_attribute) AS combination_name, (SELECT GROUP_CONCAT( DISTINCT CONCAT(agl.name) SEPARATOR ", " ) FROM ps_product_attribute pa2 JOIN ps_product_attribute_combination pac ON ( pac.id_product_attribute = pa2.id_product_attribute ) JOIN ps_attribute a ON ( a.id_attribute = pac.id_attribute ) JOIN ps_attribute_group ag ON ( ag.id_attribute_group = a.id_attribute_group ) JOIN ps_attribute_group_lang agl ON ( ag.id_attribute_group = agl.id_attribute_group AND agl.id_lang = 1 ) WHERE pa2.id_product=p.id_product AND pa2.id_product_attribute=pa.id_product_attribute) AS attribute_name FROM ps_stock_mvt sm INNER JOIN ps_stock_mvt_reason_lang smrl ON ( smrl.id_stock_mvt_reason = sm.id_stock_mvt_reason AND smrl.id_lang = 1) INNER JOIN ps_stock_available sa ON (sa.id_stock_available = sm.id_stock) LEFT JOIN ps_product p ON (p.id_product = sa.id_product) LEFT JOIN ps_product_attribute pa ON (pa.id_product_attribute = sa.id_product_attribute) LEFT JOIN ps_product_lang pl ON ( p.id_product = pl.id_product AND pl.id_lang = 1 ) INNER JOIN ps_product_shop ps ON ( p.id_product = ps.id_product AND ps.id_shop = 1 ) LEFT JOIN ps_image ic ON ( p.id_product = ic.id_product AND ic.cover = 1 ) LEFT JOIN ps_image_shop ims ON ( p.id_product = ims.id_product AND ic.id_image = ims.id_image AND ims.id_shop = 1 AND ims.cover = 1 ) LEFT JOIN ps_supplier s ON (p.id_supplier = s.id_supplier) LEFT JOIN ps_product_attribute_combination pac ON ( pac.id_product_attribute = pa.id_product_attribute ) LEFT JOIN ps_product_attribute_shop pas ON ( pas.id_product = pa.id_product AND pas.id_product_attribute = pa.id_product_attribute AND pas.id_shop = 1 ) WHERE sa.id_shop = 1 AND sa.id_shop_group = 0 AND sa.id_product_attribute = COALESCE(pa.id_product_attribute, 0) GROUP BY sm.id_stock_mvt HAVING 1 ORDER BY date_add DESC