The LGBTQIA+ acronym stands for Lesbian, Gay, Bisexual, Transgender, Questioning, Intersex, Asexual.

According to the American Psychological Association (APA), Sexual orientation refers to an enduring pattern of emotional, romantic and/or sexual attractions to men,  women or both sexes. Research over several decades has demonstrated that sexual orientation ranges  along a continuum, from exclusive attraction to the other sex to exclusive attraction to the same sex.  However, sexual orientation is usually discussed in terms of three categories: heterosexual (having  emotional, romantic or sexual attractions to members of the other sex), gay/lesbian (having emotional,  romantic or sexual attractions to members of one's own sex) and bisexual (having emotional, romantic or  sexual attractions to both men and women). 

Transgender is an umbrella term for persons whose gender identity, gender expression or behavior does  not conform to that typically associated with the sex to which they were assigned at birth. Gender identity refers to a person’s internal sense of being male, female or something else; and gender expression refers to the  way a person communicates gender identity to others through behavior, clothing, hairstyles, voice, or body  characteristics. While transgender is generally a good term to use, not everyone whose appearance or  behavior is gender-nonconforming will identify as a transgender person. 

The APA has outlined ways to be supportive of transgender family members, friends, and significant others: Educate yourself about transgender issues by reading books, attending conferences, and consulting with transgender experts. Be aware of your attitudes concerning people with gender-nonconforming appearance or behavior. 

• Know that transgender people have membership in various sociocultural identity groups (e.g., race, social class, religion, age, disability, etc.) and there is not one universal way to look or be transgender. Use names and pronouns that are appropriate to the person’s gender presentation and identity; if in doubt, ask. 
• Don’t make assumptions about transgender people’s sexual orientation, desire for hormonal or medical treatment, or other aspects of their identity or transition plans. If you have a reason to know (e.g., you are a physician conducting a necessary physical exam or you are a person who is interested in dating someone that you’ve learned is transgender), ask. 
• Don’t confuse gender nonconformity with being transgender. Not all people who appear androgynous or gender nonconforming identify as transgender or desire gender affirmation treatment. Keep the lines of communication open with the transgender person in your life. 
• Get support in processing your own reactions. It can take some time to adjust to seeing someone you know well transitioning. Having someone close to you transition will be an adjustment and can be challenging, especially for partners, parents, and children. 
• Seek support in dealing with your feelings. You are not alone. Mental health professionals and support groups for family, friends, and significant others of transgender people can be useful resources. Advocate for transgender rights, including social and economic justice and appropriate psychological care. Familiarize yourself with the local and state or provincial laws that protect transgender people from discrimination. 

References: 

https://www.apa.org/topics/lgbtq/transgender

https://www.apa.org/pi/lgbt/programs/transgender 

https://www.apa.org/topics/lgbtq/orientation