This is the 14688th most frequent Polish word.
psychologicznej
"Psychologicznej" means "psychological" in English, in the feminine singular or plural genitive/dative/instrumental form.
In this sentence, 'psychologicznej' is an adjective in the genitive case describing 'pomocy' (help).
Potrzebuję pomocy psychologicznej.
I need psychological help.
Here, 'psychologicznej' is an adjective in the locative case related to 'tematyce' (theme).
To jest książka o tematyce psychologicznej.
This is a book about psychological themes.
'psychologicznej' would be used instead of 'psychologiczne' when qualifying a feminine noun in its appropriate case; here it is an adjective for illustrative purposes.