How can be translated to predicates the following two sentences:
Every person has someone who defends him/her against attacks of others.
Some people are only defended by pacific people.
It's not clear for me:
1 - how to deal with the "others" in the first sentence
2 - the second sentence is true for people who are not defended by anyone?
Addendum added to respond to the OP's (i.e. original poster's) revision of the problem.
$P(x,y)$ denotes that Person-y defends Person-x whenever Person-x is attacked by any Person-z such that (Person-z $\neq$ Person-x) and (Person-z $\neq$ Person-y).
Then, for all Person-x, there exists a Person-y such that $P(x,y).$
There exists Person-x such that Person-y is not pacific implies that it is not the case that $P(x,y)$.
Comments:
The 2nd response could be alternatively be phrased as
There exists Person-x such that $P(x,y)$ implies that Person-y is pacific.
Also, I have (moderately) blurred the distinction between being defended and being defended against an attack by others. Technically, they are not equivalent. That is, if you are being defended against an attack by others, then you are being defended. However, just because you are being defended, that does not necessarily imply that the defender is defending you against an attack by others.
Addendum
Responding to the OP's revision of the problem.
$Q(x)$ denotes that Person-x is pacific.
$A(x,y)$ denotes that Person-x attacks Person-y.
The $\neg$ sign is to used to negate an assertion.
To the OP:
There is an obstacle to my completing the answer. Please see this article on MathSE protocol.
Before you revised your posting, you were merely asking how to convert a statement into symbolic logic. Now, you have taken your posting further, and are requesting that a MathSE reviewer actually solve a logic problem.
In accordance with the protocol article, I am not allowed to do that until you improve the quality of your posting.