This is the 5371st most frequent Japanese word.
ser
The word "ser" is not Japanese; it is Spanish for "to be."
In this sentence, the word 'seru' (です in Japanese) is used as part of the copula verb to describe someone's profession.
彼は理髪師です。
He is a barber.
Here, 'seru' (です) identifies characteristics attributed to the subject, '猫' (cat).
猫は静かで甘い存在です。
A cat is a quiet and sweet creature.
'Seru' (です) links a subject, '私たちの目標' (our goal), to its defining concept '成功' (success).