What is the ability to marry that is mentioned in the hadeeth which encourages marrying?
Question

                What is meant by the words man astataa’ al-baa’ah (whoever is able to) in the hadeeth in which the Messenger of Allaah (peace and blessings of Allaah be upon him) encourages young men to get married?.
Praise be to Allah.It was narrated that Ibn Mas’ood said: The 
    Prophet  (peace and blessings of Allaah be upon him) said: “O young men, whoever among you is able to, let him get married. Whoever is not 
    able to, he must fast, for it will be a shield for him.” 
Narrated by al-Bukhaari, 5065; Muslim, 1400 
A shield means protection against committing 
    immoral actions. 
The scholars differed concerning the meaning 
    of ability here, and there are two opinions. Some of them said that it means the ability to afford the expenses of marriage and spending on one’s 
    wife; others said that it means the ability to have intercourse. There is no conflict between the two meanings, so what it meant is that whoever 
    is able to have intercourse and can afford it, let him get married. 
Al-Nawawi said: 
The scholars differed concerning the meaning 
    of ability here, and there are two views which boil down to the same meaning. The sounder of these two views is that what is meant is what the 
    word (al-baa’ah) means in Arabic, which is the ability to have intercourse. So the meaning is, whoever is able to have intercourse because 
    he can afford the expenses of marriage, then let him get married. Whoever is unable to have intercourse because he cannot afford the expenses of 
    marriage, then he has to fast in order to control his desire.  
Sharh Muslim, 
    9/173 
Ibn al-Qayyim said: 
With regard to the phrase, “whoever among you 
    is able to, let him get married” – the word al-baa’ah was interpreted as meaning intercourse, and as meaning the expenses of marriage. That 
    does not contradict the first meaning. 
Rawdat al-Muhibbeen, 
    p. 219 
Shaykh al-Islam Ibn Taymiyah said: 
The ability to get married is the ability to 
    afford the expenses of marriage, not the ability to have intercourse because the hadeeth is addressed to those who are able to have intercourse. 
    Hence those who cannot afford it are commanded to fast, for it is a shield. 
Al-Fataawa al-Kubra, 3/134.